Blend modes from your PSD
Glows, shadows and blush painted with layer blend modes, brought in from the PSD and kept through export.
1. Paint with blend modes
In your painting program, set the layers' blend modes as you normally would: a cheek blush on Multiply, an eye shine on Linear Dodge (Add) or Screen, a soft light on the hair on Overlay. Save as .psd (Krita .kra and Clip Studio .clip work too).
2. Import
File > Open with the file, or File > Import Artwork… to add it to a model you already have open. Each layer's blend mode comes in with it. Vivid Light comes in as Linear Light; a mode Ayatsuri2D doesn't know draws as Normal, and the Log says which layer it was.
3. Check and change them
Select a mesh and look at Properties > Blend mode. Change it there if you like: the canvas shows the result straight away. Properties > Alpha blend sets how the mesh's transparency combines with what is under it; leave it on Over unless you need something else.
See Blend modes for every mode.
4. Repaint without losing them
Change the art and use File > Re-import Artwork…: the new pixels go into the meshes you rigged, and a blend mode you changed in the PSD comes in too. Keep folder and layer names the same so the layers find their meshes.
5. Export
The blend modes need moc3 version 5.3 to come out as they are. Every other version draws each mesh with the closest of Normal, Add and Multiply, and the export dialog says how many meshes that touched.
VTube Studio and OpenVT don't open 5.3 yet. For them, export 5.0 and check the model still looks right; a blush on Multiply and a shine on Add are already among the three. The Render window and thumbnails draw every blend mode, so a GIF or video of the model keeps the 5.3 look whichever version you export.