Tsukuyomi began existence as a hanging scroll portraying a full moon, which awakened as a tsukumogami after persisting for over a century. This form of supernatural being emerges when aged, everyday objects acquire spirits. The scroll holds cultural importance, historically utilized in Buddhist dissemination and Japanese artistic practices such as tea ceremonies, where its display signifies the host's aesthetic taste.

In his humanoid manifestation, he possesses a round, moon-shaped face and can freely transition between his physical scroll form and his animated tsukumogami state. His personality inclines toward self-importance; he frequently delivers philosophical pronouncements and wisdom to fellow tsukumogami. This conduct often leads others to view him as tedious or excessively prideful, though indications exist that his condescending attitude may originate from his object's historical value and artistic prestige.

Residing within the Edo-period lending shop Izumo-ya alongside other tsukumogami and the human siblings managing it, Tsukuyomi contributes to the shop's functions. He aids particularly in gathering information and resolving community mysteries that surface among the townspeople. His moon motif and observant disposition correspond with his role in watching events and offering insights, though the available sources do not elaborate on his specific backstory or development beyond these established traits.