Key Points

- Moon god and one of the Three Precious Children 

- After killing his sister's representative, she refused to occupy the sky when he does, thus explaining why day and night are separate

Brief Bio 

Tsukuyomi was the second of the "three noble children" born when Izanagi-no-Mikoto, the kami who created the first land of Onogoroshima, was cleansing himself of his kegare while bathing after escaping the underworld and the clutches of his enraged dead sister, Izanami-no-Mikoto. Tsukuyomi was born when he washed out of Izanagi's right eye. However, in an alternative story, Tsukuyomi was born from a mirror made of white copper in Izanagi's right hand.

Tsukuyomi angered Amaterasu (who in some sources was his wife) when he killed Ukemochi, the megami of food. Amaterasu once sent Tsukuyomi to represent her at a feast presented by Ukemochi. The megami created the food by turning to the ocean and spitting out a fish, then facing a forest and spitting out game, and finally turning to a rice paddy and coughing up a bowl of rice. Tsukuyomi was utterly disgusted by the manner of which the exquisite-looking meal was made in, so he killed her.

Amaterasu learned what happened and she was so angry that she refused to ever look at Tsukuyomi again, forever moving to another part of the sky. This is the reason that day and night are never together. This is according to one of the accounts in the Nihon Shoki. Tsukuyomi does not have such significance in the Kojiki, in which there is a similar tale about Susanoo-no-Mikoto killing a similar food megami named Ōgetsuhime, who is often conflated with Ukemochi.