In the early ideas for Chapter 4, Mysterious Forest was snowy and had a design similar to Snowdin. After some time, the concept and the forest location changed, so the following concepts depicted it as a water-themed forest. Eventually, we settled on the familiar fantasy forest in purple-pink tones. And in the early story drafts, Seam was originally meant to become an antagonist over time, until I came up with Hervé de Bayard VIII.