Kurobara shôten (1975)

A lean Asian guy with short black hair is in most of the scene, moving between two others in a bedroom. The main action starts with a three-way on a bed — guy eating one girl out while the other jerks him off, then they switch. You see a wide shot of all three on the floor later, one girl riding him from behind while the second goes down on her. Camera stays wide for most of it, lighting’s artificial but clear, shows sweat and movement well. The oral parts are detailed — lots of close body angles when they’re swapping. No rough stuff, just steady hardcore sex with natural pacing.