As the the main character of To Love-Ru, Rito has relationships with several characters and has his ups and downs with a lot of them. Most of whom are females who are in love with him, others, however have shown slight interest in him and it's unknown whether they have feelings for him too. The female characters' impressions of him are quite polarizing, as some find him to be truly kindhearted and innocent but clumsy, while others find him as a misbehaving and shameless pervert. They either love him, hate him or both. Either way, Rito's life is filled with a vast variety of different acquaintances, almost all of which have just as many positive traits to them as they do negative. Rito also has feelings for some of these characters.
Family
Mikan Yuuki
Mikan is Rito's younger sister. As children, Rito and Mikan were very close, and Mikan still called him "Onii-chan". Because their parents were not often at home, Rito looked after Mikan and they spent their time together all the time, walking and playing outside together. Unlike Rito, who has grown up to become very clumsy, awkward and anxious, especially around women, Mikan has become hard-working, confident, and good with housework, far surpassing her older brother's maturity and reliability. She stopped calling him "Onii-chan" and doesn't quite look up to him and respect him the way she had before.
Nevertheless, the two of them are still very close. Rito always considers Mikan as his one and only precious little sister, and has shown that the thought of losing her would be too much for him to bear. And Mikan is happy taking care of Rito at home, even though he very often does a great deal of chores and housework himself. Until Lala's arrival, it was still only the two siblings together at home, and at one point, she felt a little lonely from not spending time with Rito lately. At first Mikan enjoyed seeing how Rito's love life with Lala and Haruna would play out, but later, she would occasionally wonder how she still fits into Rito's life. However, the two's relationship as siblings have apparently gone well and, as said by Momo, that, like before, are taking baths together at times just like regular siblings do.
Thanks to Nemesis, Mikan now understands Rito's occasional tumbles and why it happens, stating it herself that it was "an act of god".
Saibai Yuuki
His dad and a manga artist, who constantly asks him to pick up Manga supplies for him otherwise he won't give him his monthly allowance. Though they hardly ever spend any time together, even on the holidays, they both do obviously love and care for one another. Being his father, Saibai often likes to tease Rito about the many girls in his life, much to Rito's embarrassed annoyance.
Ringo Yuuki
Rito's mother, who works as a fashion designer traveling around the world and as such is rarely home. While they clearly care for each other, he is shown to be embarrassed by her unusual habit of touching and stripping girls to check their sizes. Rito loves his mother, despite her embarrassing behavior, and gets his hair and eye color from her.
Celine
Celine was Lala's gift for Rito's 16th birthday. Originally Celine was a multi-story, monstrous, sentient sunflower kept in the backyard of the Yuuki residence. Although seemingly monstrous, Rito cared for her deeply and considered her as family, to which she responded with a similar caring love. When Celine seemed to have contracted a deadly disease, Rito was fully dedicated to finding the Luckberry to cure her. With the help of his friends, he journeyed to the S-level danger class planet Misletoe to retrieve the antidote, only to return to find Celine all dried up. But in reality, she was germinating, and from her single seed, she emerges in the form of a human-like infant girl with a flower on her head.
Rito cares very much for Celine and finds her both cute and innocent, taking her for walks, playing with her and watering her along with all the other flowers in the garden even though it's not needed. While he can get annoyed at her for causing trouble for him via Lala's inventions or her childish mind, he still considers her to be one of the largest parts of his life, treating her like a proper baby sister/adoptive daughter while taking high responsibility for her when he looks after her and making sure she has a fun life while doing so.
She seems to view Rito as her parent because of how he always takes care of her and because of her child-like appearance and closeness with him, she is often mistaken for his daughter. Even Rito's mother asked who the mother was, apparently not curious who the father is.
Deviluke
Lala Satalin Deviluke
At the beginning of the series, Rito was already having love troubles with his crush Haruna, and when Lala suddenly appeared in front of him, she only brought him much more trouble. But as the series progresses, he becomes very good friends with Lala, and even falls for her romantically. Rito even states that he feels uneasy when Lala is not around. Rito started out very shy, inexperienced and incompetent around women, until being forced to get used to the troublesome and shameless Lala, which greatly helped him become more comfortable around Haruna and women in general.
While she can annoy him often and cause him a great deal of problems, Rito has come to love Lala deeply for her kind and caring personality and everything she has done/is willing to do for his sake, even if her help doesn't benefit him in certain situations. He's become extremely forgiving of Lala for any trouble she may unintentionally start, and deeply respects her as both his unofficial "girlfriend" and wife-to-be.
A lot of times, Rito is willing to risk his well-being even his life for Lala. For example, when Black, a hit man, pointed a gun at Lala, Rito stood in front of Lala and refused to move away. It is because of all of his positive traits that she believes he is the most dependable person in the universe.
At the end of the original series, Rito confesses his love to Lala, while also telling her that he loves Haruna as well. Lala is ecstatic about this, however, noting that once their marriage is official, Earth laws will no longer matter, and he will be free to marry both Lala and Haruna. Rito is shocked by this, stating that Lala is "too open-minded" (Chapter 162).
At first, it appeared that Lala was quite childish regarding her love for a generally unreliable boy, but as the series progressed and Rito gradually matures and shows his kinder side, it would appear that Lala was somewhat right about him and truly did see something special in him. When Rito goes to comfort and give advice and encouragement to a heartbroken Nana, Lala notices that Nana has cheered up, and she states that it's as expected of Rito (To Love-Ru Darkness Chapter 21).
In To Love Ru Darkness, Rito still loves both Haruna and Lala. And while he states that Haruna is the one he "loves first", it is immensely implied through his actions around the both of them that this is chronologically speaking and that he loves the two of them equally. While his main objective is to confess his love to Haruna, he does show his love for Lala as often and as appropriately as he can, and keeps it in mind and often frets over how to manage his feelings for both without causing the situation to hurt anyone. As the series progresses, Rito considers Momo's Harem idea; however, he quickly shakes it off the first time.
Overall, Rito has developed a very maturing, connected relationship with Lala, going with her on errands, weekend activities, after school events and just hanging around the household like a regular couple. The two of them are very nearly boyfriend and girlfriend (with all the other girls' in Rito's life being the only thing keeping the two of them from actually hooking up), and share a very complicated chemistry that goes beyond a typical boy-girl crush; one that is still developing and becoming a more understanding, mutual love. Though he can usually get irritated by accidents caused by her and/or her inventions, he still has an incredibly open mind and heart to her personality, and great love for her caring, innocent child-like side (when it doesn't cause problems or stress), as well as her customarily kind and loving self, and is almost always open to strengthening their relationship further.
Lala had put aside her own love for Rito until he had finally confessed to Haruna, but with some encouragement from Momo, Lala began acting like her old clingy self to Rito and still acts childish. With further help from Momo, she now approaches him in a more adult way, like coming to him in the bathtub and asking for a kiss. But because of the kind of pressure Rito has about the Harem plan and the situation with Nemesis, he rejects it due to the intense matters at hand, although Lala understands that he must be going through a lot of complicated things and instead kisses him on the cheek and tells him she will be waiting until he's ready, which Rito both appreciates and is surprised by.
At the beginning of Chapter 77, Lala suggests to Rito to have dates alternately with her and Haruna because both have confess their feelings to Rito. While Rito was initially going to reject this idea he fought back to all the memo he shared with Lala and realised how painful it would be to loss her that he started cryin. With this, Haruna accepted Lala’s idea that Rito date them both.
Momo Belia Deviluke
Rito is not as romantically attracted and attached to Momo as he is with her older sister, Lala, and he notes that Momo is more mischievous and cunning compared to Lala. Rito does grow to trust her and consider her a good and dependable friend, as she protects him from danger, and would want to also be there for her as well. He relates with Momo quite well, and goes along with whatever mishaps she creates much more easily than he does with Lala's mischief. Although he still has difficulty getting used to her perverted tendencies, he seems to understand that it's the way she is, and is sometimes open to/tolerant of her sexual desires, so long as they're not too extreme or risqué.
Rito has grown to find a great deal of confidence in his relationship with Momo, talking with her about different issues in both of their lives on a (normally) mature basis. Because there are other girls who love Rito, Momo constantly tries to get him intimately closer with them and herself, (sometimes through very chaotic and even poorly-executed plans), thus creating the Harem plan. She says the reasons for doing this is to make everyone happy, but in truth, it's because she doesn't care whether she is second or third, as long as she is loved by him and wants to be by Rito's side all the time. Although he shakes it off at first, he slowly considers it, especially after seeing Run's true feelings towards him.
Rito seems to start getting more interested in Momo (sexually) as seen in Darkness Chapter 73 where he has a dream about pushing Momo down and grabbing her breasts on purpose, while it actually was Lala in his futon at the time.
In the Chapter 77 Momo has confessed her love for Rito and have explain to him "The Harem Plan" was created by a weakness in her heart, but still, she wants to become the number one in Rito's heart
Nana Astar Deviluke
Even though she can be abusive, rude and short with him, Rito stills holds Nana in high regard as he does with both her sisters. While she can annoy and even anger him through her thoughtless comments on his 'perverted ways', he does enjoy being around her like all the other members of the household.
He has, multiple times, comforted and helped her through hard times, helping fix her broken friendship with Mea, (with an added hug for comfort), giving her advice about getting along with family and assuring her that men doesn't care about women's breast sizes.
Rito has admitted to her, (while Momo was in her body), that she has a very unique and wonderful personality, and holds her in high esteem when she proves her maturity on occasion. It is quite possible that Rito may even have feelings for Nana, shown by events such as when he felt embarrassed after hugging her out of nowhere to help her calm down, and almost kissing her when Momo, again in Nana's body, talked to him kindly and offered it to him.
In Chapter 35 of Darkness, Nana has shown some concern about the kind of things Rito might be going through.
Sainan High
Haruna Sairenji
Haruna has been the girl of Rito's affections since before the start of the series purely due to her kind, caring, and forgiving nature that's very much like his own. She essentially represents the most normal and peaceful relationship Rito could have had among his love interests. In many ways, Haruna would have made the perfect girlfriend for Rito, as she is similarly shy and modest, understands and loves Rito's kind and gentle nature, is very patient and forgiving of Rito's perverted clumsiness, and has also harbored affectionate feelings for him. Although Rito owes much to the bold and extroverted Lala for the friendship he now enjoys between himself, Lala and Haruna, he now has both Lala's growing place in his heart and Haruna's loyalty and friendship to Lala to add to his indecisiveness.
Rito greatly cares for Haruna while also loving her. He comforts her whenever she feels frightened or awkward, and will go to extraordinary lengths to ensure her happiness and safety, much to her appreciation. While not exactly having a boyfriend/girlfriend relationship, the two are practically halfway there. He manages to get along very well with her, talking with her when he can summon the courage to do so and verbally appreciates her caring side to him and others around her.
Despite their somewhat intimate relationship, they still address each other by their last name (Haruna calls Rito "Yuuki-kun", and Rito calls her "Sairenji"). In Japanese culture, people who are close to each other often address their partners by their first name, and sometimes, they add honorifics (-kun, -chan, -san, etc) to determine their closeness. Judging by this, their relationship may not be as stable and close as that of close friends, though both are trying their best to overcome their shyness. However, Rito calls her "Haruna-chan" in his mind, in contrast with Nana calling him "Yuuki Rito" in her mind.
Later on in Chapter 54 in the manga, they accidentally kissed. Both have mixed feelings about their accidental kiss with the one they love, and the next day, they are too flustered to face each other. But after pressure from Oshizu and Momo, both are about to finally confess their love to each other. But at the very last second, Haruna apologizes for the accidental kiss, and Rito simply forgives her, leaving their relationship in a currently awkward but good place.
On chapter 75, Haruna confessed to Rito after defending him from Sainan High's male students because they were chasing him around. After she went into equipment room with Rito, she was happy to know from Rito that a harem plan was not possible in his opinion and confessed to him, to which in return Rito replied, but the author left a cliffhanger by not stating what he replied.
In Chapter 76, both decide to act as a couple but Rito refuses into a real relationship because he also loves Lala as well. Because he spent sometimes with Lala and starts crying which Lala notices, because he doesn't want to leave Lala as well.
Kenichi Saruyama
Kenichi Saruyama is Rito's perverted male friend. They have been friends for a long time and he is Rito's only real male friend. Saruyama is aware of Rito's crush on Haruna since before the start of the series, and he also understands Rito's incompetence around girls well enough that he wasn't at all surprised that Rito failed yet again to confess his love to Haruna. Saruyama has made some attempts to help Rito get together with Haruna.
Although they are friends, they both have certain dislikes towards each other. Rito doesn't like how other students see them grouped together when Saruyama starts acting and talking like a pervert, and Saruyama (along with almost every boy in the school) envies Rito for being close to Lala and with so many other popular girls, even though he already has feelings for Haruna.
Saruyama has a crush on a girl named Riko Yuusaki, who, unknown to him, is actually Rito, transformed into a girl by Lala's inventions. Saruyama is no less a pervert and a loser around "Riko" as he is any other time when he talks about girls, which disgusts Rito.
Yui Kotegawa
Being a strict, high-strung and no-nonsense girl with little tolerance for unacceptable behavior and an impression that boys are generally shameless, it is no surprise that she often has a negative impression towards Rito, (claiming that he's even worse than the Principal). In addition, she is often a target of Rito's perverted clumsiness, being caught in many provocative situations with him, much to her dismay and Rito's heartfelt and excessive apologies. Although she will likely never stop believing that boys are always shameless, with Rito being no exception, overtime, she comes to accept that Rito is different from most boys. As she gradually understands and appreciates Rito's kindness and accepts that Rito is still shameless but not a bad person, Yui warms up to him and grows to like him and her love for him grows more and more. While Rito doesn't seem to have any romantic feelings for her in return, he has shown to find her attractive, as evidenced by how embarrased he was being alone with her in her room.
Rito also tends to compliment Yui on relatively small matters, such as her "cute" cat-pattern pool floaty and her yukata, and is even willing to come forward and talk with her on casual terms as if there were no awkwardness between the two.
Rin Kujou
Rin dislikes Rito's perverted clumsiness, especially around her, Aya and most of all Saki, and doesn't hesitate to hit him for it with her wooden sword (sometimes with a real sword, and on one occasion, she used a gun on him). One time, she and Aya requested, or rather forced, Rito to arrange a meeting between Saki and Zastin, and when he helped them, Rin has shown a slightly better understanding towards him (even willingly smiled at him), but unfortunately, that did not last long before Rito's clumsiness struck again, ending her short-lived respect for him, although she still acts quite formal towards him.
She has shown kindness and hospitality to Mikan, and finds the younger sister to be a lot more reliable than her brother and has a better relationship with her. He has shown to be very greatful when she help his sister when she wasn't feeling well. Mikan agrees with Rin that he can be clumsy but tells her that he can be reliable when one is in trouble, however she was unable to see him the way she does, but eventually does later.
Despite showing resentment towards him, Rito willingly risked his life to save her from being possessed by the sword Bladix, standing up to the sword's consciousness and expressing about how she has those close to her, which greatly touches her. Afterwards she appears to have changed her impression of him. She is now grateful to him, but this time in a clearly more bashful way, which is highly uncharacteristic to her usual composed and aloof self, and she likely has begun to grow affectionate feelings towards him (To Love-Ru Darkness Chapter 33).
Tearju Lunatique
Tearju temporarily became Rito's home room teacher when she heard that Yami had been staying on Earth and was attending his school. Though she can be somewhat absent-minded and oblivious around him, leading to awkward situations between the two, Rito still seems to respect and enjoy her company, seeing her as a very passionate link to Yami's lighter side and has instantly come to her aid on numerous occasions.
After Yami opened up to him about her past with Tearju, Rito became eager to help them reunite with each other so that they may restore the life and happiness they once had together. When Tearju becomes Yami's homeroom teacher, Rito, with help from Mea, successfully persuaded Yami to return to school, in the hopes that she and Tearju might become close to each other again.
Tearju is fond of Rito and hopes that he and Yami would improve their relationship. She is also very forgiving of his clumsiness, especially since he has accidentally violated her numerous times since her arrival.
Trans Weapons
Golden Darkness (Yami)
She was initially hired to kill Rito by Lacospo (one of Lala's suitors), but after learning that Rito is not at all what Lacospo described him to be, she turned on him and spares Rito, but still claims that she will kill him eventually and will stay on earth until her mission is complete (even though the job is technically over). Later she confirms to him that her mission is only an excuse to stay on Earth and warns him not to make her too angry. Yami probably knows that Rito isn't a pervert like everyone thinks and just hates it when he sees her naked (Chapter 77), and she doesn't hesitate to use her powers to give him a powerful punch in the face, despite it not being his fault.
Yami appears to have love-hate feelings for Rito. She convinces him, and perhaps herself as well, that he is still her target. Like other female characters, his kindness slowly grows on her, like when she was feeling sick from overusing her powers and he carried her to Mikado's clinic, and when he protected her from another assassin sent by Lacospo, and when he refused to take advantage of her while she was uncontrollably infatuated with him under the influence of Celine's pollen. She calls him an idiot for showing kindness to an enemy, but also makes it clear that she doesn't hate idiots, sometimes showing a sweet smile that is rare to her. She also notes that being around him makes her feel safe, a feeling she does not often experience in her unhappy life as an assassin (and notes that it reminded her of her life with Tearju). Rito is the only person she has opened up to about her past.
In the beginning, Rito always seemed afraid of Yami whenever she was around, but as the series continues, Rito's fear of Yami seems to have lightened (although he still shows fear of her sometimes) and has shown to care for her. He would get mad for her sake and even worry about her well being, despite him being her target, there's something she finds strange about him.
Later on, Yami had developed some feelings for Rito. She got advice from Mea, Momo, and the teacher into getting along and much closer to Rito. Those feelings have been confirmed when she confessed to Mikan about her love towards Rito after being caught buying some love-advising books (Darkness Chapter 70)
In Chapter 72, after saving Rito from Kuro, Yami has finally confessed her love. However, she said she doesn't want to be an obstacle between Rito and Lala's relationship. She is now less violent with Rito and tries hard to increase her cooking skills with Mikan's help.
Mea Kurosaki
Mea is interested in Rito, especially when Nana called him a beast. Mea seems to find pleasure in being licked, and has a deep desire to have Rito lick her body, and to do perverted things with her, which she playfully teases him about, by asking him to do it despite being around other people.
When Rito spoke to her and questioned if some things she learned from her Master Nemesis could be wrong, Mea punished him by controlling him with her psycho-dive ability, forcing him to lick and molest her body, and at the same time sharing the sensations with him, which she believes he finds very uncomfortable. However, she unintentionally shared with him her deeper feelings of being uneasy, lost and lonely, which she angrily continued to deny, still convincing herself that she is a weapon.
Mea was at first opposed to Rito's desire to reunite Yami with Tearju so that they could be happy together again. But recently, after speaking with Rito, she decided to help him persuade Yami to attend classes and see Tearju again, grudgingly accepting Rito's insistence that Tearju sees them as her little sisters and the importance of filling the gaps between them.
Rito cares for Mea, and wants her to embrace friendship and tries to convince her that she is not alone. It's unknown what Mea's true feelings towards Rito are, as she finds his persuasion to accept humanity annoying, yet she still continues to act cheerfully around him.
Overtime, Mea grows rather fond of Rito, and even decides to invite herself into Momo's Harem Plan, which Momo is reluctant to accept. She wishes to assist in the Harem Plan in the hopes of helping Nana and Yami become more honest with their feelings for Rito, but also because Mea is very perverted and still desires Rito to lick her body.
Nemesis
Nemesis is a sadistic and demanding girl who planned for Yami to return to being a cold hearted assassin again, starting with killing her target, Rito. Recently, that doesn't seem like the case anymore as she tries to become friends with Rito (in her own erotic way) to observe their lives more closely. She says that he is a fool for trusting people, but despite this, she is very (sexually) interested in him and finds his nervous expressions towards her arousing and
Because of Rito's ability to bring the transformation weapons, Yami and Mea, closer to humanity, rather than leaving him alone she wants him all to herself as her servant, making him do things like massaging her shoulders, commenting and exaggerating his technique on pleasuring women, and even sneaking up on him in the bath. Wanting Rito all to herself as her servant, she essentially set herself up as an enemy to Momo's harem plan for Rito, telling her to give up on the plan.
She also teases Rito from time to time, but some of her jokes are pretty extreme such as accidentally turning Rito into a baby and giving him to Kotegawa.
However, just as he is with all other girls, Rito is considerate and caring to Nemesis as well, which he greatly demonstrated when he took pity on her and offered to allow her to live inside his body until she can recover after her battle against King Gid Lucione Deviluke, having seen the good inside of her and believing that she withheld the capability to change. He bravely convinced the Devilukean king to let him save her life and stop her acts of terrorism himself by taking her under his wing and showing her the beauty and fun of life, even if it means allowing Gid to kill him as well as Nemesis if she continues her ambition. Believing that he has no obligation to help her, Nemesis finds Rito willingness to save her and trust her with his own body very strange, but nevertheless accepts his offer, which she will use to survive for future entertainment.
Run Elise Jewelria
Run first fell in love with Rito when they accidentally kissed each other (in her male form). Since then, she considered Lala her rival for Rito's heart and has tried many methods to get his attention that would lead to certain misunderstandings, occasionally running towards him and landing in an awkward manner, which greatly annoys him. Along with Kyouko, they are the only two out of all the girls that like him that refers to him as "Rito-kun", which is interesting in and of itself, seeing as their relationships don't seem particularly close enough to be on a first name basis (with the -kun honorific).
In To LOVE-Ru Darkness, Run becomes a famous idol. She has also greatly matured around Rito and becomes closer to him on their date. During their date, Rito realizes that he hardly knows anything about her. From this date Rito is now aware of how deep Run's feelings are towards him, but she is saddened with the fact that Rito would never see her as a real girl while sharing the same body with Ren. This was the case until Run and Ren reached "adulthood", causing them to split bodies. Since then, Run is determined to try harder to gain Rito's affections.
In Darkness Chapter 35, it's possible that Rito is begun to have feelings for her, as dreamed about her naked and kissing him (along with Haruna and Lala). However, he turned down on her, due to his claiming that he is an useless, indecisive guy and he feels he did not deserve Run's feeling, plus his feeling for Haruna is still strong and tormenting him. Nevertheless, since Rito and Lala are not officially dating, this in turn encourage Run to win Rito's affection even more, going as far as Run telling not to lose to Haruna or Lala.
Ren Elise Jewelria
Ren sees Rito as his rival for Lala's love, so he tries constantly to prove to her that he is more manly than Rito by challenging him to completely pointless challenges (which Rito doesn't care about and Lala isn't even aware of). During one of their squabbles, Ren accidentally kissed Rito, infuriating both boys, and causing Ren to hate Rito even more. Consequently, the kiss also caused his (yet-to-be-introduced) female alter-ego to fall in love with Rito, which Ren also blames him for.
As of To Love-Ru Darkness, Ren seems to no longer make any effort to try and impress Lala, perhaps due to being featured less frequently in the story. It's unknown if he has accepted Rito as the one Lala loves or still tries off-scene to impress her. He does still care about Lala. Ren seems to have since matured from what he was before, and put most of his animosity towards Rito behind him.
He and Rito no longer seem to be against each other anymore and may have established a better relationship. However, he reminds Rito how kind Lala truly is and questions him if he is taking advantage of her kindness, which Rito thinks deep down that it might be true. Including Run, Ren advices him not to do anything to make girls cry.
Kyouko Kirisaki
Kyouko is a famous idol who works alongside Run. They first met when Run wanted to introduce Rito as her boyfriend, which Rito agreed to pretend to be. During their meeting, she revealed to him that she is a human/alien hybrid who controls fire. Still unknown to him, Kyouko realized about half way through that he was only pretending to be Run's boyfriend.
Kyouko likes Rito's innocence. Unlike other girls, she doesn't hit or use her abilities on him when he sees her naked after a mishap, and she finds him cute when he blushes and likes to make fun of his shyness. Kyouko is very supportive of Run's feelings. During her visit at Sainan High to give a lecture, she was actually there to learn more about him for her friend, but unexpectedly started to develop her own feelings for him after he saved her from a swarm of rampaging fans and carried her like a princess. She has kept this feeling hidden from Run.