He is the class officer for class 3-3, along with Yukari (and later Akazawa Izumi). Teshigawara is his childhood friend.

Teshigawara thinks he is the dead person and got into fight with him at the balcony. Suddenly he fell from the balcony but he doesn't die. In the manga, he broke his leg but in the anime, he went to Mochizuki room with an angry expression, but after that he went missing.

Kazami believed that Kouichi is the dead one and goes insane, killing Anzu and Aki from behind.

Later, when he tries to kill Kouichi saying that because of him Yukari is dead, Izumi knocked him out with an iron rod. She says he doesn't deserve to live as he killed two classmates, and when she's about to kill him saying that now he can follow Yukari in death, Izumi is stopped by Chibiki. However, Tomohiko dies later because of his injuries and Naoya seemed very affected by his death.
(Source: Another Wikia)