Yakkai na Bokura(1999)

Yakkai na Bokura

Sou and Keigo, who were already best friends have recently becomes lovers. Sou loses patience with Keigo who refuses to make any progress on their love life at all. To make matters worse Keigo actually forgets to bring a birthday present to Sou's party...!?
Also in this book, there's a side-story about Sou's dad. It's Mamoru's and Hiroki's high school story.