This monster is based on the Shinto deity of the moon, also known as Tsukuyomi-no-mikoto and Tsukuyomi-no-kami. The name "Tsukuyomi" is a combination of the Japanese words for "moon" (tsuki) and "reading" (yomu). Another interpretation is that his name is a combination of "moonlit night" (Tsukiyo) and a verb meaning "to look at" (miru). Yet another interpretation is that the kanji for "bow" (弓, yumi) was corrupted with the kanji for yomi. Yomi also may refer to the Japanese underworld, though this interpretation is unlikely. It is also interesting to note the apparent morphological parallelism with the Japanese word koyomi, which means "calendar" and is believed to possibly be derived from a compound of the obsolete Old Japanese word ke (generally believed to have meant "days") and the gerund of the Japanese verb yomu, which means "to read" in the modern language, but originally had meanings varying from "to chant," "to compose (poetry)," "to babble," and "to count" (as in the Japanese idiomatic expression, saba-o yomu, which signifies the act of falsifying one's age).
Tsukuyomi was the second of the "three noble children" born when Izanagi, the god who created the first land Onögörö-shima, was cleansing himself of his sins while bathing himself after escaping the underworld and the clutches of his enraged dead wife, Izanami. Tsukuyomi was born when Izanagi washed out of his right eye. However, in an alternate story, Tsukuyomi was born from a mirror made of white copper in Izanagi's right hand.