I played with the male MC only POV because I wanted to try out the dungeon crawling experience and save up all the scenes for later, when I feel like fapping. I haven't gotten around to the fapping yet, but I can tell you about the gameplay.
It's half baked. Almost passable but lacking the necessary depth to make it actually an enjoyable experience. First of all, the combat is basically like those "bump into monster to exchange blows until one of you dies" kind of thing. You know, like Enchanted Cave and various other similar games, just without any depth or puzzle elements.
There are a few sets of equip upgrade for attack, defense, HP, and a couple of accessories. That's the extent of your progression, and really, the dungeon wasn't designed to be fulfilling or enjoyable. It doesn't even have a boss, as far as I can tell.
To make matters worse, if you actually wanted to pay off the dept in 10 days to qualify for happy end, you probably shouldn't even be buying equipment. Just take the sis who can one shot anything two times per day to the top floor (dodging all the monsters on the way there) and get the expensive loot. Actually playing the progressive dungeon crawling will basically not get you the happy end for any reasonable playthrough. And if you didn't want the happy end anyways, what's the point of this whole system? You can just exit the dungeon immediately and pass the days if you want the most NTR ending.
Plus, there is a huge campus map that is essentially entirely pointless. Other than one uselessly annoying fetch quest that makes you run around the whole place, you never do anything on campus. I've never found any of the standard free roaming scenes in a game like this, where you might find various "hidden" sex around campus. There is basically nothing of the sort, and no side quests or story related reasons that lead you to certain areas of the campus. The entire game is sleep, go straight to dungeon, buy/sell stuff in shop, go to sleep.
I actually haven't gotten to the fapping part yet... so I can't talk about the scenes. But the initial set up and the bond of these two are explored just enough (pretty good set up without taking overly long). Based on my coomer experience, I think the H part will be pretty good when I get around to checking the scenes. As far as NTR progression is concerned, it seems promising for fappability.
Translation seems to be typical Saiky edited MTL that they pass off as manual trasnlation. There are a fair amount of errors, pronoun mixups, and sometimes lines being attributed to the wrong character. Also, the editing gets noticeably sloppy after the intro.
The annoying thing about this game to me is that with just a bit more effort, this gameplay system could have been fun. Oh well.