xukmi/KKShadersPlus: Recreated Koikatsu shaders ... - GitHub
Since the query is specific, here is the quick install guide: xukmi.shaders.fx
// 1. Constants and Textures texture2D BackBuffer; sampler2D sBackBuffer Texture = BackBuffer; ; xukmi/KKShadersPlus: Recreated Koikatsu shaders
Understanding xukmi.shaders.fx: A Deep Dive into Post-Processing Effects sampler2D sBackBuffer Texture = BackBuffer