Great, big building in the forest, located less than a 10 minutes drive from the Volcano Parks Entrance. It was very quiet while I was there, so there was almost too much space ;-) The kitchen is really big and well stocked (including an oven) so easy to self cater. Volcano Village only has small stores though, so better to shop beforehand (I went to Keeau).
Satoshi stopped by both days I was there and it was really nice to talk to him. He's traveled a lot so has some good stories.