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...