Psychometrer Eiji - Vol. 1 Ch. 4 - Moebius, Demonic Killer 4

[MangaDex]

 

[SirMoogle]

Killer's boner game is weaker than Eiji's.

 

[JackHuncho]

A weak boner for a weak mind.

 

[abconline]

mobius ring so of course it's the math teacher lol