Ten Narita

A boy at the same school as Karin. After he mistakenly confesses to Karin in place of her older sister, he halfheartedly agrees to an alliance with her; Ten is to provide information about his older brother, whom Karin has a crush on, while Karin provides relationship advice regarding her older sister, whom Ten has a crush on.

After Karin reveals to Ten that, in reality, she likes him and not his brother, he affirms his love for Karin's sister but acknowledges Karin's own challenge to him: to see which of them can enter a relationship with their loved one first.