Hi - this is great and glad to see you are partnering with noone77521. The whole reason I made this account originally was to ask about MMDShow plugin!
I had some questions about the settings, I couldn't find a definition of what some of these do:
1. Enable Mouth Physics Mesh
2. Enable Breast Physics Mesh - Guessing this is soft breast physics?
3. Enable Lower Physics Mesh - I am guessing this is soft glute physics
4. Motion Position State - What does on vs. off do?
5. Motion Rotation State - What does on vs. off do?
6. Close Lower Bones
7. Force Disable IK
1. About Mouth\Breast\Lower Physics Mesh Switches. It's all about soft physics switches. The soft physics of the mouth is disabled by default. If it's on, it will cause the person's lips to be blown up when the dance moves are too big.
2. About Motion Position\Rotation State Settings. This will set the default values for the plugin control joints. Just keep the default if you don't know its purpose.
3. About The "Close Lower Bones" feature. This option and The "Motion Position\Rotation State" options are special requests from some players who may need to do something special with the person in the scene during the dance. I don't know what they'll do either. Strange Humans.
4. About The "Force Disable IK" feature. Some older versions of MMD don't have IK, so you can enable this option to avoid IK fixes causing motion anomalies. If you need more guidance on this, please contact @sfishere .
Mostly open setup options are used to handle some special needs, if you're not sure what a feature is used for, keep the defaults.