I think soushi is on the spectrum, no?

... I dont think so?

He shy

Nooo he just has a stutter

He’s not stuttering because of a speech impediment alone, he’s AFRAID of speaking, he started listening to metal so he wouldn’t have to speak to people. He tries to look scary so he seems unapproachable (he let his bangs down to look like the guy at the store). He’s hesitant, he gets nervous, speaks even less and looks stressed when he wants to make a big decision, like when he hesitated for one week before going into the cake shop to submit his application. He may like things that autistic people usually don’t, like extremely loud music, but that’s specifically because it helps and relaxes him, it’s an outlet that allows him to just be — no pressure, no expectations from others. That’s why I think he’s on the spectrum, or has some sort of neurodivergence.

I think readers can interpret fiction in their own way and there's no right or wrong. To me it's not clear, I think his speech could be affected by selective mutism, anxiety, other mental health issues, low self-confidence or autism.