Nice beginning! ;)
This story looks promising already.

That was cool... The premise is familiar, but interesting, and I like Shotaro's rudeness, haha. The Black Smile seems pretty corrupted, forcing him to join like that.

This is AWESOME!
Love the premise—kind of similar to Revenant actually what with the soul draining and that (o.O)—eh, but who cares. This is sooooo cooool! *fangirl squeals*

"Shotaro walked over to his teacher and stared at his hair piece, analyzing it from all angles."—lmao, could totally see this bit happening in my head, anime-style XD

Uwaaaah ! The old man attack was really well written... I hate it when there's just one person walking behind me... Especially when they're really close and seem to be following you... Gah, that was really creepy! (TT_TT)

"Shotaro Minami, would you like to join the Black Smile?" / "No." — Ahaha! He has an awesome personality!

Great job Dan-nii! Gonna subscribe to this one. It's gonna be kick-ass! :3

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Couple of nit-picky things:

*The bolded words displaying the setting are unnecessary. The location is pretty easy to gauge from what actually happens in each section.

*If you're going to capitalise Impetus, make sure it's always capitalised!

*Watch your grammar in dialogue.