In the Nabeshima clan’s castle town, lord Tango-no-kami kills his chief retainer Mataichirō for refusing to offer his sister as a concubine. To cover up the crime, the scheming retainer Buzen buries Mataichirō’s body in the armory walls and offers his own daughter instead. But Mataichirō’s vengeful cat, Koma, possesses Buzen, seeking revenge.
