Niizuma jigoku (1975)

Starts with this brunette with a lower-back tat lying face-down on the bed, legs spread just enough to tease. Then the blonde comes in—she’s got a cloth tied around her mouth, full lips still pouting, and they go straight into a deep kiss while the blonde’s hands are all over the brunette’s tits. Asian guy in glasses shows up later, picks a big black dildo off the shelf, and starts fucking the brunette doggy style while she’s still got the gagged blonde licking her pussy. Camera gets right in there for close-ups of the gag stretching the blonde’s mouth and the brunette’s tat flexing every time she gets slammed. Lighting’s dim but you can see every drop of spit and sweat—no fancy editing, just raw, sweaty action.