Momioka Risa

Risa Momioka is Haruna's and Mio's best friend and Rito's and Lala's classmate. Her favorite thing to do is to grope the girls breasts 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 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. This is shown in the manga chapter: 147 and on episode 10 of Motto To Love Ru Trouble episodes.

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

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

Haruna Sairenji
Risa's friend who occasionally gropes Haruna, sometimes saying they've "grown"