this game is to tedious and hard, i keep getting bad endings x>x
I'd recommend checking the Steam community guides for reference. They are quite detailed, although from personal testing, some of the facts are a bit misleading. For example, if your sister's interest is high enough, you don't lose trust when reading a naughty book, which the activity list guide doesn't mention.
On the side note, if you are really down bad, my recommendation is to farm trust until 100 so you can enter bathroom together (which apparently is actually prevented on the first few days when doing an NG+ surprisingly), since this is by far the best method to raise trust, interest, and lust for free. In the meantime, it's highly recommended to keep her mood at love and, at minimum, above good since she'll give out free items like the dumbbell, iron sandals, adventure books, drinks, or even naughty items (depending on the relationship stages).
