Momioka Risa

Risa Momioka is Haruna's and Mio's best friend and Rito's and Lala's classmate. She is very fun-loving, mischievous and perverted. She enjoys talking about naughty things, teasing Rito, and her favorite thing to do is groping the breasts of other girls and whisper naughty things to their ears.

Appearance
Risa is an attractive girl with dirty blond hair and dark brown eyes. She has a curvaceous figure (though not at the level of Lala or Yui) and seems to have some trouble keeping some men at bay. Of all her class mates she is probably the most willing to use her figure to attract attention, save for comedic scenes.

Rito Yuuki
It is not known what Rito and Risa feel for each other, but it could be assumed that they are generally friends, or at least acquainted through Haruna. While various other girls consider Rito to be a pervert, Risa knows that he is an innocent boy to a fault and likes to tease him about sexual subjects.

Rito wishes that the naive Lala would stop taking lewd ideas from Risa and Mio. And Risa doesn't take Rito's rejection of sex and temptation seriously, and likes to play with his shyness around girls and occasionally gropes the breasts of other girls in front of him.

It has been shown that Risa might have feelings (or at least lusts) for Rito but it hasn't been detailed if she was serious or joking. In chapter 147 and episode 10 of Motto To Love-Ru, she takes a much closer and bolder approach in teasing him, but it is still not clear what her true feelings for him are.

Lala Satalin Deviluke
She is good friends with Lala and likes groping her breasts. She often gives wrong or lewd ideas to her questions.

Mio Sawada
Risa's friend and partner in crime, she also enjoys groping girls' breasts and whispering in their ears.

Haruna Sairenji
Risa's friend, whom she occasionally gropes along with her friend Mio, sometimes saying they've "grown".