City of Sin (1971)

Starts with a brunette standing, brushing her hair while the others sit on a couch. They’re all slim, white girls in their 20s — one blonde with wavy hair, one with long dark brown hair, and a brunette. The blonde starts undressing, removing her top, and the scene gets intimate fast. They use a green towel or fabric to tease each other, taking turns posing topless and playing with it. The camera gets nice close-ups of the blonde’s body and the brunette’s playful expressions. The whole thing feels natural and soft, with good lighting and angles. No guys, just them exploring each other in a casual setting.