Nubatama Bamboo 1K Gold. This stone is slightly porous, quickly saturating. It produces a fine mud, is pretty hard and rapidly produces a fine mud mostly composed of metal swarf. Perhaps a bit harder than the Ume 1k small stone. No glazing noted.
The knife used is a Kikuichi gyuto. I believe this stainless knife is VG10 or a similar steel. The video is short because the stone was done much faster than expected. Very impressive stone! A very hard stone, something a Shapton user would like who appreciates harder stones. A bit harder than the Ume 1k smaller stone or stones similar to it. Also razor users would find this attractive. People who like a muddy stone should look at the 1500 Nubatama stone instead.
Did not like the feel of this stone at all. It feels like it has a "drag" to it. The stone is very porous,it took a week to dry after use. It seemed to cut ok but nothing overly impressive. There are better stones for the money.