Kyogoku Tei operates as the hidden mastermind and principal antagonist, orchestrating events from behind the scenes. He acts as superior and patron to the Ongyou trio—Mataichi, Ogin, and Nagamimi—supplying them with targets for their missions of supernatural retribution. Initially commissioning the Ongyou to eliminate protagonist Momosuke to conceal it, he later deemed Momosuke useful for his broader schemes.

Using the alias of feudal lord Danjo Kitabayashi, he commits inhuman acts to fulfill a grand plan: plunging Japan into eternal darkness. This plan hinges on constructing and activating the Flame Lance, a magitek superweapon cannon. The weapon draws power from ritualistic human atrocities and suffering, often depicted in pornographic atrocity prints. His ultimate goal is unleashing this weapon to destroy the existing order.

Kyogoku Tei employs two enigmatic messengers, the Hermits (one Black, one White), to relay his orders to the Ongyou; these Hermits occasionally shapeshift into young girls to manipulate the trio. He recruits other morally compromised individuals, such as the murderer Tatsuta, after the Ongyou attempt to deliver judgment upon her. Unaware of his full intentions, Tatsuta assists by orchestrating massacres and coercing prisoners into violent reenactments necessary for the Flame Lance’s reconstruction.

His methods exploit human darkness—hatred, ambition, and cruelty—to achieve his omnicidal goals, manipulating both subordinates and victims whose suffering powers his weapon. This exploitation ultimately causes his downfall. During the final confrontation, the collective darkness of all those he used and betrayed consumes him, resulting in his destruction. The Hermits are accidentally destroyed by him in this process, and Tatsuta perishes in the inferno triggered by his defeat.