Gosai no joukou: Uzukinaku shiri

Original title: 後妻の情交 うずき泣く尻

Sakakibara marries Miho, a young wife who is a generation younger than him. People envy him, but Sakakibara enjoys his young wife's lush body while also struggling with his own. The two originally had a relationship as boss and secretary. Miho encourages Sakakibara, who is depressed over his breakup with his ex-wife, and the two eventually become romantically involved.