everything's crossposted on both ao3 and fanfiction.net, if you'd rather read there
Stories by angstea
Honeymouth
In which Hitoshi Shinsou is reincarnated as Hitoshi Kamado, and is the moon to Tanjiro Kamado's sun.
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Naru...
Bakashi-sensei
In which Kakashi reacts poorly to a nickname, one thing leads to another, and suddenly traumatic experiences...
Supernova
In which Katsuki replaces Sasuke Uchiha after the Massacre, and he is not okay (but these dumbass shinobi are...