This is quite a nice game! The art styles from both the overworld and the battle scenes felt quite disjoint, but I do love both of them. The cat is super cute! The battles are very undertale-esque, and are difficult but surprisingly good! I do like the fact that you should be able to finish the game without using the book, and I am guessing there will be a separate ending, but I should confess that I can't win the eyeball bat fight with the book, so I don't know what will happen next.
For some criticism, the first thing is that the game is way too short. I felt like things had just started but it's already at the end of the game, but I guess in a one-week jam this is too much to ask for. I'd also say the combat was way too unfair. The claws are alright, but the randomised bats are just too RNG to effectively evade. The book fight is a bit easier but still, it's up to how RNG feels like it each time you play. I'd say simply adding a bit more invincibility frame should make the game much easier than it should be.
Anyway, this is a very nicely built game and I like it quite a lot! Well done!