Chikan shindai ressha (1975)

This one’s got a pretty hot setup – three Asians, two girls and a guy, getting intimate on what looks like a train or bus. The girls are both slim with long dark hair, one with glasses. They start with some conversation and flirting, then things get more intense. The guy and one girl get close, then the other girl joins in. At one point, one girl is on her back, and the other girl is on top, giving her oral. The camera gets in close on some of the action, which is pretty smooth. The girl with glasses looks like she’s in her 30s, the other girl and the guy look like they’re in their 20s. One thing that stands out is how natural it all feels – they’re not just fucking, they’re also touching and reacting to each other.