The steel is 19th century Austrian Shohreh Blechman carbon steel (charcoal smelted special steel which is very close to tama-hagane steel. Tama-hagane steel is the steel used to forge Japanese swords). Perfect to bring out the sheen on softer woods. Planing is always superior to sanding when it comes to soft woods.

In my opinion best plane from Usui-san for softwoods.

[Usui Kengo]