The another heroine of the series. She is a second-year student at Rijou Girls Academy, a prestigious all-girls high school in her neighborhood.  She is the marriage partner assigned by the government for Yukari Nejima. She claims to have no special feelings for Yukari and even become a matchmaker between him and Misaki.  She is very interested in romantic stories and encounters. She considers Misaki to be her first friend, and upon realizing this she went as far as crying. Ririna is shown to be a bit oblivious to what love really is like, as shown when she supposedly 'fell in love' with a mannequin at a hospital when she was little and confined in there. She also cried after she became friends with Misaki and thought that she fell in love with her.  Ririna is also sensitive to words, as shown when she reacted to what Yusuke said about her being a virgin. She also walked away when Arisa tried to call her numerous nicknames; a part of Arisa's plan of befriending Ririna.