Because it seems no one here has watched A Silent Voice:
Swamp is(in theory) Shouko, the deaf girl.
Shouya is the protagnoist who bullies her when they're in middle school, one of the "pranks" involve stealing her hearing aids a d throwing them away
Unvote: Swamp
Vote: Stoopid Unikorn
Forgive me for voting you, Swamp, I'd never hurt a cinnamon roll.
I wouldn't believe Shouya to be mafia though, as he has already realised he was a ****ty person by high school which is when the majority of the movie takes place.
Still, if he's stealing Swamp's hearing aods, that's a problem.