Zodiac sign:
Gemini

Blood type:
O

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 color:
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). Currently attending the same highschool as Futaba under a new last name (probably his mother's). He eventually admits to being "Tanaka-kun", and while acting cold and uncaring towards her most of the time, his nice side becomes gradually more prominent.
(Source: Ao Haru Ride wiki)