I have no idea what this bonsai is, and it has recently lost all of its leaves.. It's still budding. I'm not sure if it needs repotting or if it's in its way out, please help!
Metasequoias are deciduous conifers so it's normal for them to drop their foliage in the fall. You should see buds along the stems which will leaf out in the Spring!
Larches and Tamarack do this too.