Kou Mabuchi (馬渕 洸)

Kou was well liked in middle-school, he liked Futaba and they had a growing relationship, but then he suddenly moved away in the middle of the school year. His parents divorced and he now lives with his father (presumably he first lived with his mother after the divorce, but when starting high school he moved in with his father instead, for unknown reasons). He is currently attending the same high school as Futaba under a new last name (probably his mother's). He eventually admits to being "Tanaka-kun," and while acting cold and uncaring toward her most of the time, his nice side becomes gradually more prominent.