@k1maaa_@NotDacie You can check "Koikatsu Blendlet" on Youtube,this guy has many good tutorials about transfering koikatsu models,shaders or animations into blender
@k1maaa_@NotDacie Koikatsu shader is build on Unity,so it's impossible to 100% replicate it in blender. So if you want perfect replication, you may need to try Unity instead.But you can try to use blender to make a shader that looks similar.