>>2890687The same answer as for the manko, Alicia Solid Kai by YY_works. That anatomical shoulder rig is basically the only way to stop experiencing this, but you can also edit motions on an individual basis to delegate arm bone twisting to the arm twist bone. There's a program for that:
https://subscribestar.adult/posts/1054941 (already linked while I was writing, but this is an English explanation). The shoulder rig has the following drawbacks:
1) Complexity.
2) IK snapping under some conditions. I observed this with 万花谷, 小雨, HWAA, Nikisa-san's motions. It appears to be fixable if you add some minimal rotation to the shoulder bones instead of leaving them at 0.
3) (Only if you wish for elbows to rotate naturally instead of slowly turning behind the shoulder to finally snap 180 degrees when you reach the limit, as in the bottom left side of the picture, old version on top.) The inability to use BDEF4 for the upper arm to avoid the "pinching" that turns the arm mesh into a sausage string. Only SDEF can fix that.
4) If you make motions for distribution, you may not recognize that an arm is twisted too much, which can result in ugly-looking child works.
I'd love to recommend PMX-VMD-Scripting tools once more as an alternative, but... picrel. There might be a way to set the model up so that it works, but I don't feel like trying to find it.
