Pocket Kanojo ~Hakudaku Ningyou~

Hideki Minami has a one-sided crush on Chiaki Horie, who attends the same school. Hideki, who lacks communication skills to begin with, only has fun interacting with bishoujo figurines and bishoujo figurine enthusiasts on web forums. One day, he discovers a way to miniaturize humans and succeeds in making Chiaki figurine-sized. He has the heroine he admires live in his room and tortures her to the fullest... [Roughly translated from product page]