Onsen de Himitsu no Otomari, 241-kaime

Ishida and Kimura have been seeing each other for twenty years...but only once a month. They manage their work, and head for a hotel or ryokan where they can relax in a hot spring bath. No one, even their closest friends know about their relationship. This month, they are together again...for the 241st time. They soak themselves in hot bath, treat themselves with good food.

"...Hey. Wanna come closer?"

"Okay."

This relaxing trip is what the mature couple live for.

(Source: Kadokawa)