So, I play the game as it intended, which means no dev mode. After playing it blindly and getting nearly all endings, here's the pros and cons of the game:
PROS:
1. The semi 3d graphic and quality is amazing, and dare I'd say one of the best I've played. Not to mention, the girl is surprisingly very expressive.
2. While at the beginning, (just like any other chikan game), there was very little action you can do and it was very easy to get caught early on, after a couple of "reincarnation?", your action option increased quite a lot and unlocked pleasantly a few more scenes that I didn't expect.
3. The story is good enough, I guess. While I get the gist of the plot, the MTL made it hard to digest, especially as someone who isn't fluent with english.
CONS:
1. As the others have mentioned, the game itself is grindy. You can only do nothing but molest her for a bit early on AND have to be patient about it since the game counts every action you do and encourages the player to play NG+ a few times to get and see progression. (But honestly, it could works as a slow burn since the only hint you get is from the text and her reaction without the dev mode.)
2. The MTL is barely good enough, which hinder the enjoyment of the story. Not to mention, I was confused with the action of "production", which was apparently sex. (Hopefully, someone picked this game to translate, or even better the dev release it to western audience.)
Overall, 5/5 for me.