Otokonoko Love Play

A guy starts dating a femboy and discovers his boyfriend has never even masturbated, so he takes it upon himself to fix that with some videos and hands-on instruction. Watching the kid squirm through porn is what actually gets him going, not the teaching itself.

From there it's less lesson plan than seduction: talking the femboy into women's underwear, laying him down, and calling it normal couple stuff. The femboy's embarrassment turns out to hide a masochistic streak, and the more he's teased the less he protests.

Play stays close to that dynamic, watching and nudging the femboy through escalating scenes voiced and drawn in 2D, with the protagonist steering how far things go rather than the femboy taking initiative himself.