Manga based on the BL game developed by Alice Blue. Each storyline has a different author:

Prologue: Akira Norikazu Kurosaki x Higuchi: Reno Amagi Kurosaki x Shimizu: Reibun Ike Kurosaki x Yamaguchi: Ryou Sakura Kurosaki x Yoshioka: Wren Tamaquis (Source: M-U)