The debug tool can be found in the top-left closet in the tavern's floor 1 kitchen. It's got a bunch of debug-only stuff letting you cheat money, stats, etc etc (and can potentially corrupt your save, so make backups!)someone have cheat?
In particular, do not use it to save your game anywhere there are walking students. It will appear to save normally, but then brick your save file when you try to load it because I have done terrible, terrible things with RPGmaker's engine, and the engine really doesn't like it sometimes. Regular saving works just fine from anywhere, just not the debug tool!