>>2275918get the UV map plugin from bowlroll, and put it on your plugin folder.
https://bowlroll.net/file/15244with the model loaded and with the V and M buttons toggled on, open said plugin and search for the material that has the mesh you want to separate, and select all the vertex that forms it, after that select the second button. doing that will highlight the mesh in the pmdview window.
in pmdview, press shift and the left button of your mouse near the highlighted material to fully select it (you can even do this in an empty space, just make sure you are pressing shift), finally go to EDIT>Selected face>Is taken to a new material or >Removed to a new material by separating the vertex.
both options will create a new material and move the selected mesh into it, and the latter will make the vertex of that mesh that was connected to the original material act on their own so you can move them without fear of fucking the original material or viceversa
