I like the concept of the school becoming a gladiator arena, and I appreciate the effort that went into both the custom assets and the battle system. Very much enjoyed those aspects of the game! That having been said, I don't think I ever really understood how battles work: because the player's options are very limited, winning or losing is a bit on the RNG side of things. I found that begging was generally the best option, since you could defeat your enemies without needing to spend MP. Also, since backing away sometimes fails to do anything, and can also occasionally recover as little as 1 or 2 MP, all the more reason to avoid relying on MP entirely. As for the items, equipment, etc. that can be purchased, I understand not necessarily wanting to add descriptions in order to keep things interesting, but because they cost so much it's difficult for the player to experiment with them. Ultimately, I wasn't able to defeat a sophomore enemy that kept appearing and couldn't clear the game.
I do like what's here, I think it's really interesting and with a bit more polish and a bit more clarity as to what does what it could be an even better game. I also got a huge kick out of the little details, like the progression of the MC's reaction to the post-battle healing, the notes left for her, anti-depressants showing up in the store for an exorbitant price, etc. I hope you continue to work on this game so we can see it at its best.