Mesudachi -

The term "Mesudachi" (メスダチ) is a compound word formed through slang morphology:

When combined, the word strips away the politeness of josei (woman) or shin'yuu (close friend), creating a term that feels raw, informal, and heavily coded. While it can be used derogatorily in certain contexts, in the otaku subculture, it is often used as a badge of honor, signifying a "female friend who is just as down bad or chaotic as I am." mesudachi