Definition

A poetic term for your first love or a safe emotional refuge—literally evoking the moon (tsuki in Japanese) as something eternally present but distant. It's the person or place you return to when life breaks you.

Example Usage

Even though we're not together anymore, she'll always be my tsukii.

Source: Urban Dictionary (https://www.urbandictionary.com/define.php?term=tsukii&defid=17694581)