Hadaka no tsukiai

Hadaka no tsukai is an idea in Japanese culture. It is the idea of spending time together naked. It is also called skinship, written "sukinshippu" in Japanese. Hadaka no tsukai friendships are not sexual. They are platonic.
A family, a group of housewives from the same neighborhood, a group of businessmen, or a group of classmates might spend time together naked at a sentō bathhouse, at an onsen hot spring, or at a health club. This makes them feel like a group.