YOU SAID:

that happens once in a blue moon

INTO JAPANESE

それはブルームーンに一度起こります

BACK INTO ENGLISH

It happens once in the blue moon

INTO JAPANESE

ブルームーンに一度起こります

BACK INTO ENGLISH

Occurs once in the blue moon

INTO JAPANESE

ブルームーンに一度発生します

BACK INTO ENGLISH

Occurs once in the blue moon