Very stylish intro and game overall, nice one. A bit hard (I didn't make it past the second level) but I'm also not too used to bullet hells so it might be just right for people used to the genre.
Gameplay wise, maybe it could wait for the monsters to get into view before shooting at you. Because on day 2 I got killed before even seeing the monster which is not fun, and kinda feels like they didn't detect me but just spam mindlessly all the time.