I'm a sucker for bones-based art haha. Good job! The only sprite I'm not too comfortable with is Hitsuji's magical girl form, her eyes look a bit too demonic for me. But maybe that would be explored in the future, who knows?
It's lighter on content than most games here, that's for sure. I think there's not much that could be done to improve it given that time constraints seem to be this game's worst enemy. But I think just switching the order of the doors would give this game a more adventure or almost puzzle vibe. As of now all doors are found in the order you find the magical girl who opens it... The last door is a nice change, but it's too little too late. Mix all of the doors! Make the background more unique, too, maybe there can be different corridors, more barriers to go through... but I really have no idea how much longer that would take. Mixing the doors seems to be the thing that would improve the game the most with almost 0 extra time commitment, I think.
By the way, I loved the transformation sequence lol.