Kikonsha desu kedo, Nani ka?

Mikado—gay, once a famous playboy and womanizer—lost his former brilliance and splendor, having a marriage of convenience. However, Mikado, who has cooled to carnal pleasures, meets a new employee—Serizawa, with whom he slowly falls in love. This guy, obsessed with sports and cleanliness, awakens our protagonist's wild fantasies and reignites his long-forgotten desire. The mysterious Serizawa, together with Mikado, who is obsessed with him, they go on a business trip and stay for the night at an onsen, where Mikado discovers an unexpected secret about Serizawa...

(Source: Frontier Works, translated)