Experimental WebXR MMD Viewer
Visit https://ii.kwaa.dev/mikumikumixed/ and click play.
MikuMikuMixed itself does not store any model/movement/music files, all of which are taken from third parties. If you want to use custom assets, you'll need to deal with file storage and CORS issues on your own.
For example, miku_v2 model for three.js is stored here: /examples/models/mmd/miku/miku_v2.pmd
Then you can get it from jsdelivr using the following url: https://cdn.jsdelivr.net/gh/mrdoob/three.js/examples/models/mmd/miku/miku_v2.pmd