The Enlargement Experience is the one hundred and fifty-sixth chapter of To Love-Ru.
Nana, distraught over her breast size, that she decides to make her bust bigger no matter what, enlisting Haruna and Oshizu, innocent bystanders, to help her with "Operation: Breasts." Nana asks Mikan if she wants in, but Mikan declines the offer. The three girls head up to Nana's room, where they try many different methods, including: massaging their breasts (Oshizu actually uses her willpower to do this) and getting an octopus from Planet Hacchi to attach its suction cups to their breasts.
After these two methods do not work, Haruna remembers something that Rito said long ago, "The important thing is not what's on the outside, but what's on the inside." Nana, knowing that Rito said that, likes him a little bit more, then vows to not only improve her outer appearance, but her inner self as well.