From Tokyopop:

After a near-fatal car accident, surgeons rebuilt Reiji with prosthetic parts and renamed him Himejima Kazemichi. It was a second chance at life... but there was no guarantee that his new body would last. As his artificial heart runs down, Kazemichi embarks on a journey to discover what his life really means, and live -- and love -- to the fullest. Along the way, he uncovers dark secrets about his past... including the organization that was responsible for resurrecting him...

The handsome and cool Arisaka has always been unapproachable. Natori attends the same university as Arisaka and is in the same class with him, so he always gets jealous every time he sees Arisaka talking happily with Professor Shima. Natori is always secretly thinking, “How I hope that he could smile at me that brightly!"

Uno is disowned by his father when the father discovers that he has a male lover, thus he relocates himself to a boarding school. There, his roommate Sakurai is annoyed about Uno's crush on his neighbor Keisuke...

Not every person can be happy about having a boyfriend that works as host. Katsuzou is one of those that have something against. To express it he throws at Tomosa (his love interest) a fire extinguisher. Luckily, it didn't kill Tomosa but it seems like he has lost his memory... What in that case will Katsuzou do?