Not bad, the puzzles reminded me of old point and click adventures in a good way. I enjoyed the writing, especially Mumei's notes.
Suggestions:
It might be nice to have some form of checkpoint to make future loops quicker.
Some kind of marker to indicate the dialogue text is still ongoing would be nice so you're not clicking around waiting for it to end when you're actually able to close the dialogue or use an item.
Bugs:
You can use the hammer on the door infinitely, I lost one loop because I thought I needed to beat it down a bunch before remembering the other doors you had to back out to see that they're unlocked.
Off that same bug, if you use a key on a door, you can still interact with the door knob to see it's locked.
Kronii's scream is really loud if she falls.