Kōichi Tatsukawa is the star pitcher of the high school baseball team. He's also the submissive boyfriend to Ryoko Enatsu.
Kōichi Tatsukawa is a main character of the manga series Take On Me (known as Domin-8 Me in U.S.) that was created by Sessyu Takemura. It originally began publication by Core Magazine's Megastore Comics in 2004.
His first appearance was in Take On Me Volume 1 CH. 6 "Arlington Road".