Aihara Kotoko played by Sato AikoKotoko is from the 'F' class and her dad is a chef. An accidental kiss with Irie Naoki of the 'A' class causes her to fall head over heels in love with him. However, Naoki is very cold to her and she has a rival Matsumoto Reiko vying for Naoki's affection. Fortunately, Naoki's mum Machiko is very supportive of her. Kotoko goes to nursing school after graduation.
Irie Naoki played by Kashiwabara
TakashiNaoki is the all-rounder in school. When Kotoko comes to live with Naoki's family, he is very irritated by Kotoko. His classmate Reiko is very much in love with him but he doesn't display any affection towards her. Naoki goes to become a doctor after graduation.
Matsumoto Reiko played by Ozawa MajuReiko is the daughter of a hospital director and does things her own way. She is very much in love with Naoki and tries very hard to win him over. Reiko delibrately spites Kotoko a few times. She even goes to the same university as Naoki in order to stay by his side.
Watanabe Junichi He is very obsessed with Reiko and is frustrated with the fact that he has to play second fiddle to Naoki. His ultimate aim is to get the top spot in school and win Reiko over.
Irie MachikoMachiko is Naoki and Yuki's mother. She is very happy when Kotoko comes to stay with them. Machiko tries very hard to bring Naoki and Kotoko together. She treats Reiko with hostility.
Irie YukiYuki is Naoki's younger brother and looks up to him as an idol. His dream is to manage their father's company with his brother. He shows his dislike for Kotoko openly because she is staying in his room and he has to stay in Naoki's room.