The high-quality natural whetstone, retrieved from beneath the waters of Asaji Bay in Nagasaki Prefecture, is highly esteemed for its exceptional value and rarity.
The process of extracting it from the sea involves desalination and drying, demanding considerable time, expertise, and effort. These meticulous steps are believed to significantly enhance the whetstone's quality.
Since the excavation concluded over 40 years ago, obtaining it has become increasingly challenging, further highlighting its scarcity.
This whetstone boasts exquisite hardness, providing flexibility while ensuring outstanding blade engagement. It also possesses a well-balanced combination of grinding and polishing capabilities.
With finely honed edges, it serves not only as a whetstone for knife finishing but also as a Nagura (a type of whetstone) for polishing other natural whetstones. Consequently, it is expected to yield a high-quality finish comparable to whetstones produced in Mikawa（三河）.