[Yen]

I'm pretty sure it's impossible to save NPCs.
In order to permanently add NPCs, you have to overwrite the level as text.
If you overwrite the level as text, it has to be updated.
If you update the level, the tile changes will be lost, since it takes a few minutes for updateboard2 to actually save.
I gave up, because I couldn't figure out how to save the tiles into the level. :/