Lessons in Love. It has a good plot for an isekai. Basically you're a teacher for ~20 teenage girls, but since you got reincarnated, you decide not to teach them and instead perv out on literally all of them. Doesn't sound very interesting, but there's a bigger plot that's so complicated I can't even really explain it. Play it for yourself and see. It also has things called happiness scenes which are terrifying and keep me coming back, even though the MC is a cum stain.