Birthday: May 27
Zodiac: Gemini
Blood type: O
Height: 176 cm
Weight: 58 kg
Best subject: Social Studies
Worst subject: Classic Literature
Favorite food: chicken nanban
Least favorite food: celery
Favorite musician: Dave Matthews Band
Siblings: one elder brother
First love: 1st year of middle school
Usual snack: potato chips
Favorite beverage: coffee
Favorite colors: blue & black
Other: His hair is part naturally messy, part perm.

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.

It's revealed that he moved away to live with his mother due to his parent's divorce. His mother's later terminal illness, caused him terrible grief and trauma, eventually resulting in his change of personality.