In Japanese folklore, Zenki (前鬼*)? and Goki (後鬼*)? are a husband and wife pair of murderous bandit Onis stopped by the Emperor Tenmu of Japan. Tenmu outwitted them and convinced them to reform into ascetic disciples. They then both became attendants of En no Ozuno, founder of Shugendo Buddhism.
Some legends say they are (or at least look like) demons or Tengus, with magical abilities, but was really just devout practitioners of Shugendo, knowledgeable in metallurgy and medical herbs.
Zenki and Goki are the servants of En no Ozuno while the protagonist and his party are in the Diamond Realm. Zenki allows the protagonist to save while Goki has the ability to fully heal the party. Zenki and Goki will also fight the party before they exit the Diamond Realm, with the two of them saying their farewells to the party after being defeated.
Zenki[]
"Origin: Japan. An attendent of En no Ozuno, founder of Shugendo Buddhism. Legends say he looked like a demon, but was really just a devout practitioner of Shugendo, knowledgable in metallurgy and medical herbs. He is the husband of Goki."
—Shin Megami Tensei A-Mode DDS Dictionary
Goki[]
"Origin: Japan. An attendant of En no Ozuno. Like Zenki, legend has it that she was a demon or tengu, with magical abilities. She is Zenki's wife."
—Shin Megami Tensei A-Mode DDS Dictionary
Shin Megami Tensei: if...[]
Zenki and Goki appear in the Nomos of Earth within the Tower of Confinement, the primary setting of Akira Miyamoto's route. Like in Shin Megami Tensei, Zenki allows the player to save their game, while Goki will heal the party.
Shin Megami Tensei IV Apocalypse[]
The two Oni return as men dressed in suits in the Messiahs in the Diamond Realm DLC. They both still serve En no Ozuno, with Goki healing Nanashi and Zenki returning him back to Tokyo.
Devil Children Black Book & Red Book (PS)[]
Zenki and Goki are obtained upon defeating En no Ozuno in Battle Net.
