Buso Renkin

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!

A homunculus embryo has lodged itself on Tokiko, and a week remains before she becomes a homunculus. Between bouts of training with his lance, Kazuki and Tokiko search for the creator of homunculus in order to obtain the antidote. Meanwhile, the Papillon Masked Creator orders his subordinate homunculus Kawazui to find the lance-wielding boy. Kawazui's desire for revenge makes Kazuki hold even tighter to his personal vow: to use the kakugane Tokiko gave him not for himself but to protect others. His first one-on-one battle with a homunculus begins!

Evading the homunculus Washio's attack, Kazuki and Tokiko fall back to form a plan. The two devise a series of high-speed attacks, but Washio's natural instinct and warrior experience sees through their plan. He slashes Tokiko, and Kazuki succeeds in delivering a single blow to Washio. But Tokiko is heavily wounded, and worse, the lodged homunculus has progressed up to her spinal cord. Kazuki fights on, and Washio feels a stubborn strength growing within the boy.