Hi, it’s Junko from Japan. Moon says TSUKI in Japanese. Here’s the Kanji writing for it.

In daily conversation, the moon is also called OTSUKISAMA, meaning “sir moon.” Women and girls often call the moon OTSUKISAMA with affection.
Moon Related Words in Japanese

O = Japanese honorific
TSUKI = moon
SAMA = Japanese honorific for a person
Additionally, we have some other words for the moon depending on the phases. I’ll introduce them and how to write them in Japanese.
MANGETSU (full moon)

The full moon says MANGETSU. MAN is a symbol that represents something filled with something to its limit.
HANGETSU (half moon)

The half-moon is HANGETSU. The HAN means half.
MIKAZUKI (crescent)

The crescent is called MIKAZUKI in Japanese. MIKA is equivalent to the word MIKKA and means “three days” or “third day.” It’s named after the fact that the crescent appeared on the third day of the ancient lunar calendar in Japan.
GEKKŌ (moonlight)

The word for moonlight is GEKKŌ. GETSU is another way of reading the moon Kanji symbol, and KŌ stands for light. The two words are connected and pronounced GEKKŌ.
If you read the Kanji combination honestly, it’d be GETSUKŌ, but the word GETSUKO doesn’t make sense. GEKKŌ is the correct one.
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