Doki-Doki E-Mail is the one hundred and fifty-fifth chapter of To Love-Ru.
Rito asks Yui if she can lend him a novel that she is reading for his dad. Yui agrees, and they exchange e-mails. Later that night, Yui finishes the book and decides to tell Rito that she has finished. But it takes nearly a half hour to write the message, as she was nervous about e-mailing him. She goes to take a bath afterwards.
Meanwhile, at the Yuuki residence, Lala and Nana are watching Magical Kyouko, while Rito is sleeping on the couch, with Momo watching him make a "cute sleeping face." His phone rings and Momo tells Rito that he has e-mails, but Rito, still sleep, asks her to take care of the message while he rests from picking weeds. Momo misinterprets the message Yui sends and thinks it's sexual. What follows are many misinterpretations by Momo, Nana, and Yui that leads to Yui receiving a naked photo of Lala, thinking it's from Rito. Momo plans to apologize to Rito later.