A New Life

S1, E1: In an abandoned factory at night, Kazuki Muto dies in an attempt to save a girl from a monster. Or does he? Kazuki wakes up the next morning as if nothing happened. But after school, when his teacher transforms into that same monster, Tokiko, the girl he tried to save the previous night, appears and tells him that the monster is a homunculus and that he did in fact die the night before! But Tokiko replaced his heart with an alchemical alloy called a kakugane that can transform into a weapon of immense power called a Buso Renkin. Now, Kazuki is about to find himself mixed up in a supernatural battle!