Onee-san wa Miinna Dosukebe!

Bandai-kun works at a public bathhouse, where he encounters a series of older women who are surprisingly forward and sexually adventurous. Each visit brings a new encounter, turning his job into a series of steamy situations.

During a trip to the beach, he finds that the same bold women are there too, eager to engage in more explicit activities. As if that weren't enough, his own sister begins to question his bathing habits, leading to an unexpected and intimate confrontation at home.