Mina is a trendy "ko-gal". She thought Ai was after Yuichiro, the guy she liked, so she turned the whole girl population against Ai. But later after she finds out Ai likes Ichinose and not Kato they become best friends. The reason why Yuichiro is afraid of her is actually because of an incident that happened when they were left in a classroom together in junior high. Yuichiro had tried to shy away from her though she never stops chasing after him. She is aware of his feelings for Ai. She hates that he does but there's one event in the manga where she tells him to just to tell Ai that he loves her. Mina is usually vulgar like Sô and like Ai said she has a tiger like personality and was ready to pounce any time. Her feelings for Yūichirō are very obvious and she knows so much about him, it almost looks like she's stalking him. Ai even says though Yuichiro will not admit it, Mina and he are very close and share a strong friendship. In fact, Yuichiro and Mina are seen together repeatedly throughout the series having their own private conversations about the events at school.