Tsukuyomi, a centaur hermit inhabiting a secluded cave near Mount Fuji, lives a solitary existence while occasionally guiding lost travelers. After rescuing two wounded individuals swept into a river, he restores their weapons and offers his name, though he deflects the reverent label of "sage" others impose. He shares vital knowledge by reciting passages from an ancient tome detailing magical wands—artifacts linked to Brights, rare beings who can harness their power, with Elves historically dominating their use.

He outlines the conflict between two opposing forces pursuing the wand: the Shield of Light, guardians of peace, and the Inferni, determined to resurrect the Dark Lord. By interpreting celestial patterns, he confirms Sonya’s survival and guides the group eastward beyond Mount Fuji to Yokohama, where an Elf enclave might aid their quest. Tsukuyomi remains detached from direct conflict but equips the protagonists with crucial insights, prioritizing practical aid over personal involvement.

His origins are shrouded in mystery, defined only by his reclusive lifestyle and familiarity with esoteric legends. No expanded accounts or additional roles in other narratives are recorded.