Houichi Koizumi

He is Hitomi's "Instead" who works in her bar and does everything including disposing the bodies, he was the only one whom was able to listen to Hitomi play the last note with her killing good and survive, was the fact that he is deaf, and it is hinted that the reason that he can respond to people normally was that he can read people's lips.

(Source: Otaku-streamers forum)