I've looked everywhere and can't find it. I see the room where you can view the game over scenes and pictures but it doesn't have an option to fight. Edit: nvm apparently you just buy it at the item shop in Jiming.
Okay new problem. I can't beat the mermaid boss. It seems only physical attacks would work very well against her or something, and I seem to be stuck with having like no attack and I don't know how to fix it. Maybe it's a bug or something but I'm stuck with some status effects seemingly permanently.
Well I saved pretty often but I don't remember exactly. But going back through my saves, the 2nd status effect shown above was one of the last battle or two that is available in that one's recollection room as shown in the image I've attached. The other two came from a battle that was one of the last 2 girls in the second row or the 2nd green thing that fits 2 girls, and I think it was most likely the latter.
In both cases, I got the status effect right before winning the battle. You might have to have the enemy burned to make it work but I don't know exactly the steps to make it happen. But then the status effect seems to just be stuck, and no amount of turns in battle, items, or useful skills can seemingly cure it. However I've found staying at an inn can fix it so it's not that big of a deal.