Kazuki finds Koushaku in his great-great grandfather's laboratory and attempts to destroy the Homunculus matter. However, due to the interference of Koushaku's younger brother Jiro, Koushaku is able to have the Homunculus embryo attach to him and is turned into a Humanoid Homunculus. He then begins to eat everyone in the vicinity until he is killed by Kazuki, who passes out from exhaustion before he is able to deliver the cure to Tokiko. Kazuki awakens to find the cured Tokiko who christens his buso renkin Sunlight Heart.