NPC won't settle down in one of my houses
Shime ji is one of the variations of the truffle. For him to settle, you need to create him a house in the mushroom biome and bring it to the surface ideally. So go underground, get mushroom biome seeds, and plant them. They can only be planted on mud, so you will have to create a mud platform. A biome starts when ~50 blocks of the biome blocks are present. Music starts playing if you succesfully made the mushroom biome. Then make him a house in the mushroom newly created mushroom biome. If he still doesn't settle, make the biome bigger.