It isn't just the the most basic thing It should have, It's the only thing It needs to have really. As for the generic sidescroller, it just not being complete ass is a damn good accomplishment considering the standards of H-games, again I agree that as a game It's pretty barebones, but so is (and forgive my blasphemy) great games like Night Of Revenge which is really just an okay metroidvania/souls-like. Judging these games as proper games is not really what they're meant to be judged as, they're usually made by one horny asian dude so that other horny dudes can play them and fap and not much else.
I wasn't at all affended or angered by your initial review, I'm trully just trying to explain why for other people a game like Syahata that delivers what they want and doesn't screw up in a way that devalues what they're here for, the porn, is a great game in their eyes. Ultimately I do believe your review hold merit, as does everyone's else, but the way you're looking at the game is wrong.