Any time he does anything to her it seems to reset, you're constantly unsure whether things are real or just in his head.
However, as an adaptation you can argue that this fails spectacularly, because of just how much it changes.
In the original comic it's a dude lusting after a schoolgirl that proceeds to molest her on the train, in this it's a story about a kid who was doing lewd stuff with his teacher (which we see some scenes of), and now he's an adult and encounters another teacher on the train that is identical to that one for some unexplained reason, and proceeds to imagination-molest her.
If this was a typical anime, the fanbase would be rioting over so many changes, so it's better to take them as standalone works and enjoy both.
overall, if you wanna enjoy some shortstack action without thinking about the plot - definitely give it a try.
