Living Dead (ASADA Nemui)

Sada is an earnest high school teacher admired by students and colleagues alike. One night while walking through the city, he stumbles upon a student being violently attacked in an alley. As he tries to call for help, Sada finds himself on the end of the attacker's blade, bleeding to death on the ground. When he wakes up on a slab in an unknown laboratory, he comes face-to-face with his savior, a scientist named Mamiya. But Sada quickly realizes that in cheating death, he has become something...inhuman. What's more, he's now fully dependent on Mamiya to survive. What awaits him in this new life of death and deadly secrets?

Note: Includes two extra chapters.