The younger sister of Lala and the twin sister of Nana Asta Deviluke. She is the 3rd Princess of Deviluke and, like Lala, is also attracted to Rito.
Momo, along with her twin, followed the example of Lala and fled from Deviluke to come to Earth. Although for entirely different reasons, both of them fled because neither wanted to study the history of planet Deviluke. Which fits perfectly with the relative childish nature of the both of them.
Momo has short, pink hair and is generally sweeter than her twin, but gets a bad attitude when Nana takes credit for what she does. Her attraction to Rito is much like Lala's, only a lot more lustful: she enjoys when Rito touches her tail and often becomes aroused when Nana refers to him as a "beast". Her tail can shoot out lightning (weird!!!)
Momo, after Rito is kind to her, for some random reason, Momo starts to develop her own not so small crush on Rito. Even mimicking Lala's habit of waking up in Rito's bed, wait for it... naked. Which is really, really perverted when you think about how old Momo actually is.
Out of the twins, Momo has a unique connection with plants and her dialer (cell phone) summons whatever plant that she happens to want at the time. Momo is usually the twin that thinks up random pranks and acts upon them immediately, dragging Nana along for the ride.
One last detail for the die hard ecchi fan, Momo has a larger bust than her twin. Which tends to cause some rather interesting dialogue.
In To-Love-Ru Darkness, Momo enrolls into Seinan High with her sister. Momo creates a plan to release the "carnivore" in Rito (awaken his sex drive) so that he will take it upon himself to create his own harem, so he can love every girl who also loves him. Throughout the new series, Momo often does even more dirt things to Rito than before such as getting in the bathtub with him, undressing in his room and licking him to get him aroused, and other such things.
She Changed her hair so that she would look like a grown up girl. She Loves Rito even more but still, she don't want conflicts on her Older sister or to Haruna that's why she made the Harem Plan, She don't even care if she is number 2 or 3 in Rito's Heart. She works Hard on doing the plan buts still Mea is always there to Ruin it even though she includes Mea in the Harem plan.