Shinshutsukibotsu! Ijigen Nikubou ~Konna Tokoro kara Ojamashimasu~

One day, while the protagonist is engrossed in his daily routine, something appears out of nowhere. Right on the crotch of an anime poster’s heroine, a fully erect 'thing' materializes! And it looks oddly familiar.
Shocked and panicked, the protagonist is already too far gone to stop. He climaxes instantly—and at the same time, the cock on the poster shoots out a stream of white fluid!
The next morning, during the rush-hour commute, it happens again. He feels the unmistakable sensation of an erection and the friction against fabric, but his own pants show no sign of it. Confused, he looks around and notices a flustered classmate nearby. Her movements sync perfectly with the soft, fabric-like sensation on his dick… and he realizes the truth.
He’s awakened to a strange superpower: the ability to teleport his dick anywhere. With this power, he can toy with or dominate anyone, completely one-sidedly.
Torn between a flicker of guilt and a desire of conquest, he begins looking for his next target.

[Translated from dlsite]