Koe no Furu Heya

Shizuka Kagurazaka, an overworked corporate illustrator, lives alone in an apartment with a soundproof room.

One day, out of the blue, he receives a friend request from his high school classmate, Fumiya Oji, who says he is being stalked. Shizuka reluctantly lets Fumiya into his home. That's when Shizuka receives an unexpected “stimulus”…

(Source: Big Comic Spirits, translated)