I wanted to find out what fonts are used in the Mystic Messenger chatroom (for possible comic purposes??) but it didn’t seem to be common knowledge in the fandom, so I did some sleuthing myself. I found most of them! The fonts I chased down are:

Sans serif: Nanum Gothic (Regular, Bold, Extra Bold)

Serif: Nanum Myeongjo (Regular, Bold, Extra Bold)

Rough sans serif: BM Hanna

These are all free for personal and commercial use and can be downloaded from the early access page of Google Fonts.

For added authenticity: Set kerning to None, increase tracking a little and only use dumb apostrophes (small straight line instead of a little ‘nine’). Also, a thin black stroke (outline) is sometimes used for extra emphasis instead of bolding.

Sadly I couldn’t find out where the cute handwriting font comes from :C