Here is an introduction to the five main characters of this series:
Akira Uehara is the protagonist of the series. He is a junior in high school, who is good-looking but is also weak and clumsy. He has little sister named Miu, who beats him around, and a best friend named Shinnosuke Senbongi, who has been his friend since elementary school. Akira also has a crush on the most violent but cutest girl in his school, Nanako Momoi. Although he knows that they are ill-matched, he cannot move on from her. Due to his more gentle personality, Akira when in Momoi's body becomes the love interest of his best friend, Senbongi. This love triangle between him, Momoi, and Senbongi becomes more complex as the story progresses.
Nanako Momoi is the female lead and love interest of the main character, Akira Uehara. She is in the same year as her classmates, Uehara, Senbongi, and her best friend, Shiina. Since her parents live overseas, she lives together with her mad scientist grandfather. At her school, her good looks win her the belle of the school, but her wild and loud personality makes her would-be admirers flee in fear. After switching bodies with Akira Uehara, she grows to like living as a guy and takes the opportunity to do things that she could not do as girl. To Akira's dismay, one of these opportunities is being the boyfriend of her best friend, Makoto Shiina.
Shinnosuke Senbongi is Akira Uehara's best friend. He is a high school junior and in the same class as Akira Uehara and Nanako Momoi. Since middle school, Senbongi has been popular with girls due to his erotic aura and his experience with girls. (He might have to thank his three older sisters for that.) As Akira's best friend, Senbongi is Akira's emotional support and caretaker. When Senbongi finds out about Akira's crush on Nanako, he advises Akira to give up and find someone else becaue he fears that the wild Momoi will make his buddy miserable. (He was right.) However, when Momoi suddenly becomes more feminine, Senbongi falls in love with her, and making sure that his buddy has moved on, hits on her. However, what Senbongi does not know is that this new girly Momoi he is in love with is actally his best friend in the cute girl's body.
Makoto Shiina is the best friend of Nanako Momoi. She is a junior in high school and in the same class as Akira Uehara and Nanako Momoi. She has an older brother, who is overprotective of her. Although she is a quiet and calm girl, she possesses hidden strengths and quirks that allows her to be best friends with the most feared girl in school. When Akira and Momoi switches bodies, Shiina does notice the change in them, but she doesn't believe that they actually changed places. (I don't think many people would. ) Instead, she thinks Momoi, who suddenly became more feminine, is finally in love with someone and her classmate, Akira Uehara, just became more masculine and attractive. Shiina later falls in love and starts dating this more masculine Akira, not knowing that she is actually dating her best friend.
Manzou Momoi is Nanako Momoi's grandfather. He lives with Nanako Momoi, lazing around and getting fat. In the beginning of the story, he invents a machine, whose purpose is to shrink human beings. He invents this machine, thinking that it will help with the problems of global warming and food storage. On the test day, instead of shrinking them, he accidently (or possibly on purpose) switches the bodies of his granddaughter and her classmate, Akira Uehara. To the Akira's dismay, he finds the switch a success and chooses not to fix the machine until Akira gathers the funds for it. Making money for the machine proves difficult for Akira because the money that he makes is used, not on the machine but on useless knicknacks that grandpa finds interesting.