Kaisei (開成) (~3000 to 5000)

Kaisei (開成) is also called a Revised whetstone (改正砥石) in Japan.

This is a highly prized revised whetstone which originates from Suzukawa Village, Higashimurayama District,
in Yamagata Prefecture in Japan. The mine was closed around 1975. This whetstone was popular because it has
strong abrasive power and leaves only shallow scratches. A middle stage Nakatoishi stone with an approximate
grit rating of 3k-5k. Uncommon to find nowadays due to its use in traditional sword sharpening where it sits
between the Binsui and Chu Nagura stones. These stones are very consistent and aggressive, very good at
bevel setting razors and knife sharpening.

Personal Notes:
Mine below feels smoother than my 4 Aizus and I was extremely fortunate to get it considering how rare they are.

1. Kaisei Wet Closeup

1. Kaisei Label

My Japanese Natural Whetstone Collection