There is little strange or unusual about a man who has fallen for a girl. It is strange, however, when the man begins following the schoolgirl he likes only to wake up one morning and find out that he has literally become the object of his affection. He, er she, does not know what to do, how to behave and how to react.

Bodies have switched and a boy is a girl, but that is only the beginning. There are new (old) friends to deal with, new (old) situations to handle and it seems like everyone is looking at the new Mari with surprise, anger or wonder. The new Mari is trying to adapt and figure it all out. It is not easy when everything is new all the time.

Mari and Yori investigate the switched bodies and observe Isao at his apartment. Yori has discovered a secret. They end up taking the bull by the horn and make their way inside his room and get sidetracked cleaning and playing video games. Mari's parents are worried and attempt to speak with her. Unhappy with the situation Mari's (Isao's) feelings boil over and she dives into a sexual fantasy involving Isao and Mari when a surprise calls comes in.

'Mari' takes sides between Yori and Momoka and the other girls. She reveals that the real Mari had called her on the phone yesterday. Mari visits Isao and surprises him. He is happy to see her and excuses himself to the washroom. Mari finds no shame in what he is doing and asks him to do it in front of her while looking at her.

She refuses when the boy professes his love and asks the girl to go out with him. She is unsure who she is or what her nature is. Then another call comes from Mari and from an unknown number. At the same time, Mari shows what she thinks of Yori both in-person and when the friend is missing.

Mari finds Yori and everything seems okay again, but an old photograph and a trip to the fun fair surface old and obscured memories involving a grandmother to the surface. Could the old Mari not even be Mari to begin with? Mari's mother is not helpful and instead is cagey.

Mari is unresponsive and catatonic. Yori forces her way into Mari's house and room to see her and is successful compelling Mari's mother to confess to what had transpired. Isao has a job hoping that the new initiative and effort shall lead to Mari looking at him favourably. A conversation with Yori does not end well.

Mari and Yori look to resolve the mystery of the switched bodies and identities after getting their hands on Isao's diary. The girls leave Tokyo to visit Isao who has returned to his hometown. Mari collapses, but is awakened to hear a message of hope.