Natsu Kuyuru Sukimono no Yado

Miharu, an otaku boy who works at a shabby inn in a hot spring resort, is in a relationship with Fujio, the inn's heir and a former porn actor. He racks his brain trying to think of a way to revive the hot spring resort, but he doesn't really know what Fujio is thinking. One weekend, Miharu attends a comic event, so Fujio invites him to his second home in Tokyo for the first time...!? A sexual love diary between a former porn actor and an otaku boy.

(Source: Shinshokan, translated)