Master Ozune Enno centuries ago bound the demon/guardian Zenki into his service to fight evil, particularly Karuma and Zenki was sealed away once the job was completed until needed again. Schoolgirl Chiaki Enno as the Enno descendant is able to break the seal on Zenki, but he is also bound in a child-sized form when not fighting evil because he is defiant so she must use the power of the bracelet which appears on her wrist to bring him to full fighting stature. The Seeds of Karuma cause people to turn into monsters embodying a vice which Zenki defeats so that he can eat the Seed. Set 3 adds demon/guardian Goki who boosts Zenki's power to the next level and usually provides a shield to protect the rest of the team of Chiaki, her Grandma Saki, Saki's brother Abbot Jukai, his assistant Kurabayashi and sometimes helping out hero Sohma Miki. When not fighting, Goki returns to his human form of a boy, Akira.

Included one-shot:
Volume 5: Kishin Douji Zenki (Pilot)