The rock is called Benten-Jima and is technically the northernmost point of Japan. It is about 1.2km off the coast of Cape Soya which is typically regarded as the northernmost point. It was a stormy day (as most days are up here in winter!) and the rock is quite a distance away, so the photo is not great, but you can see several sealions clustered at the right-hand end. Those paler blobs all over the rock and along the shoreline are more sealions.
