(Maruka) Shou-hon-yama is the best grade stone from Nakayama sold by the sole miner of this mountain, Hatanaka Natural Sharpening Stones Stone Industry. Any (well basically, but there are many that are not so good, so we have to test all of them before selling) Nakayama stone that has this stamp (unless it's a fake) is guaranteed of its highest quality. Maruichi Maruka stones were quarried before the mining was taken over by Hatanaka family, when the owner of the mine was Kato family. Maruka's (= circled "Ka") "Ka" is Kato's first character "Ka".

A stone that was specifically intended to be used for polishing Japanese razors (most of the "razor size stones" are simply smaller size stone that is similar to genuine "razor stones"). Simply the finest quality.

The surface. Maruka Shouhon-yama stamp. The stamp that's pressed only on best of Nakayama stones from Hatanaka family.

The back.

High cutting strength, but very fine.