Please check the photos. This is a natural Kozaki Aoto whetstone quarried in the Kozaki area of the Tamba region, Kyoto, Japan.

Kozaki has long been known as a source of natural whetstones, producing a wide range of stones from Aoto to finishing-grade Awasedo. This particular stone is a highly practical Aoto, well suited for medium-finishing to pre-finishing work on kitchen knives, planes, chisels, and other edged tools. It is especially well suited for single-bevel knives, allowing the user to refine the edge while enjoying the smooth and pleasant sharpening feel characteristic of natural stones.

Compared to typical Aoto stones, this example is somewhat harder and denser in structure. As a result, water absorption is relatively moderate, and the sharpening surface remains stable throughout use, providing a calm and controlled sharpening experience. In addition, swarf releases easily from the surface, reducing loading and allowing for comfortable sharpening over extended periods.

During use, the stone produces a fine slurry while maintaining good cutting ability, gently refining the edge without being overly aggressive. It performs particularly well when used after a synthetic stone in the #1000 grit range, where it effectively bridges the gap between coarse sharpening and the final finishing stages. It also transitions exceptionally well to natural finishing stones.

The stone excels at creating a practical working edge with a pleasant degree of bite and cutting aggression. Whether used as a preparatory step before a finishing stone or as a final edge preference in its own right, it offers excellent versatility. It is also well suited for preparing the foundation of an attractive kasumi finish, naturally enhancing the contrast between the hagane and jigane.

Today, quality Kozaki Aoto stones have become increasingly difficult to find. This stone is appealing not only as a practical sharpening tool but also as a valuable example of the natural whetstone heritage of Kyoto's Tamba region. Please note that these are not for beginner sharpeners since they're harder to use. These are natural stones meaning that every single one of them are different so my measured sizes are not accurate. This is a lifetime investment for people who live sharpening their tools, do not hesitate to ask me your questions.”

Dimension :52-57mm×225mm×27-57mm ( Approx.) 

Weight: 1885g