This is a Juniper (Juniperus) of unknown species, although, as it will have originated from garden origin raw material, it will be a variety or even a hybrid grown by the horticultural trade.
In any case this is an impressive tree that is just about in the chuhin size class despite the overall height being 52cm. The very significant trunk at 15cm. across at the base features just what you would expect from a mature juniper bonsai image, extensive jin and shari deadwood, all of which could do with being highlighted by cleaning and the application of line sulphur preservative. The branch canopy has a spread of 60cm. and all that is required to complete the image is that foliage refined by a combination of pruning and perhaps some judicial wiring. It is planted in a nice quality Chinese unglazed oval ceramic that measures 37x30x9cm.