Cure Blood

"You're the only one in this life where I can't die." A storyteller that will touch your soul is born. This is the story of a doctor who gives blood and a vampire who doesn't age.

The new doctor, Tadayuki, suddenly underwent a transformation. He desperately wanted blood like a vampire, and his aging process had slowed dramatically. Tadayuki attacked his senpai Juji, disappearing after telling Juji that he had died. But Juji sought out Tadayuki and offered him a helping hand, telling him, "I'll examine you and give you blood, too." They never could have imagined that it was the beginning of a secret they would keep for decades.

(Source: Shodensha, translated)