Recently some problems with loading custom JCMs (Joint Corrective Morphs) were reported. It turned out that the code contained a hack to avoid problems with reloading JCMs, and that piece of code didn't work well. The problem should be resolved in the latest development version, but looking into this made me better understand how custom JCMs work and how they are related to the corresponding FBMs (Full Body Morphs).
First we import Aiko into Blender with Mesh Fitting set to DBZ File.
However, there is a catch. The final shapekey values are multiplied with the strength of the Aiko FBM (Full Body Morph). If the Aiko FBM is not imported, which it wasn't since we only imported the pJCMs, behind the scenes the FBM strength is set to 1, and everything is fine. But let's see what happens if we import the Aiko morphs.