Mizu no nai puuru (1982)

Skinny Asian girl with long black hair is lying on a tatami mat in a dimly lit room, completely naked. Another person, possibly male, joins her on the mat — they’re both close to the ground, moving slowly into oral and then penetrative sex. The camera stays wide for most of it, showing the full room, low light reflecting off their skin. She goes down on him first, sucking his dick with her mouth open wide, head moving back and forth. Then she flips over, gets on her hands and knees, and takes deep thrusts from behind while gripping the mat. Later there’s a shot of her peeking through curtains, fully exposed, like it’s a different scene or flashback. The whole thing has a quiet, almost voyeuristic feel — no music, just raw sounds and natural movement.