One night, Kazuki Muto jumps in to try to save what he thinks is a girl in distress from a monster and instead gets impaled through the heart. The girl, Tokiko, is actually an alchemic warrior with a Busou Renkin, name of Valkerie Skirt, with the mission to exterminate Homunculi. She implants the only other successful work of alchemy than the Homunculus, the Kakugane, to take the place of Kazuki's heart. The Kakugane resonates with his fighting spirit and forms a Busou Renkin (in his case a spear) so he can fight the Homunculus monsters who prey on humans. Kazuki joins with Tokiko to battle with the Homunculi and protect his friends and his sister Mahiro.

Buso Renkin:

• 1. A New Life
• 2. The True Form of Homunculus
• 3. You Became A Little Strong
• 4. Another New Life
• 5. For the Sake of the Person Who Must Be Protected
• 6. Butterfly of Black Death
• 7. If You Suspect Hypocrisy
• 8. Night In the School Dormitory
• 9. The Hayasaka Sister and Brother
• 10. You and I have A Affinity
• 11. Two People Separated By Death
• 12. Carnival
• 13. Signs Of Death
• 14. Who are you?
• 15. Existence of Middle
• 16. New Power
• 17. When the Night Ends
• 18. Flight Journey
• 19. If Only You Can Protect
• 20. Putting in Thoughts and Power
• 21. GONE INTO FLAME
• 22. The Required Decision
• 23. BOY MEETS BATTLE GIRL
• 24. When You Die That Is When I Die
• 25. Substitute Is Not Required
• 26. Period