Saimin Z

The timid and socially awkward protagonist encounters a strange, shadowy man at dusk who bestows upon him the powers of hypnosis. He soon meets his own alter-ego, who states "I'm you. Another you who does whatever you want".

He calls out to the girl reputed to be the cutest in the whole class. The girl stumbles, the light in her eyes disappears, and she stands still.

"Now, do whatever you want with it. It's your puppet now."

[Edited from DLSite]