Tonari no Douki no Renai Jijou

Baba can't stand the loud moans coming from the guy in the apartment next door. But one night, in a fit of frustration, he ends up getting off to them... and is horrified when he realizes it was a man's voice that pushed him over the edge! Embarrassed and in shock, he steps out onto his balcony, only to come face to face with the very neighbor he'd just been listening to...!?

(Source: Libre, translated)