Lobo in Classroom to Different Monster?

Any idea on how to make the chest still have an item in it / give a specific item after defeating the monster? I haven't looked too hard so I could probably figure this out if it is possible, but currently I only know of "have monster drop item".

You can do that with an event. The way I do it is place an invisible NPC on the same tile as the chest. When you talk to the NPC it triggers the battle with a pack from number 256 to 511. Then when the battle is over you add an item of your choice to the inventory and display a dialogue box with a message and change the tile of the chest for an open one.

You must also set an event bit that will be used in the entrance event of the map to make the tile change effective when you re-enter the map after opening the chest. Finally you deleted the invisible NPC and reflect this in the entrance event as well. There can be some variant of that kind of event but basically it's this.

I made locked chests that you can only open with a key or a pick lock that way...