[Tensho] Natural Whetstone Yamashiro-mei Koppa Stone 325g with Iyo-mei Stone

The power of locally sourced and produced materials!!

Please refer to the box dimensions listed above. Weight indicated is the packaged weight. Please use this as a reference for size comparison.

The grain is clear, making it easy to work with and yielding a high rate of usable material when dividing the stone. We encourage you to actually try facing and dividing the stone yourself to verify the properties and performance differences of the whetstone.

It contains a variety of types, sizes, and shapes. For blades you intend to sharpen, use a stone with ample size to create a flat surface. Otherwise, divide the stone into smaller pieces and use it as you would a sword polishing stone.

It is composed solely of **first-class mineral deposits** from the easternmost part of Ukyo Ward, Kyoto City, along with comparative samples.

The Umegehata whetstone comes exclusively from Mukonouchi-cho in Umegehata, known for Nakayama and Koyama, and extending to Okudono-cho, the origin of Kyoto whetstones and famed for its菖蒲谷 (Shobudani).

This is a set that doesn't compromise on quality, avoiding stones bulked up with inferior material. The authenticity is revealed by how it splits. The stone preparation was primarily carried out by trainees under the supervision of an instructor with over 15 years of experience in the Yamamoto-style forging technique. We believe they have successfully split, sorted, and created a colorful assortment of items, so please check the images.

We encourage you to try splitting it yourself and observe the significant differences in physical properties, including the vibrant colors. (Prepare a flathead screwdriver, mallet, safety glasses, and gloves.)

Having even one soft, reddish-pink piece is a stroke of luck. (Please understand this depends on the lot.)

Clear grain in the original stone easily produces a flaky slurry resembling a film.

Sharpening granules with directionality are arranged on the flakes, resulting in surprisingly strong sharpening power.

The grain size increases with the breakdown of the flakes when water supply is restricted.

The sliding between flakes is lubricated by the crushed mud of tenacious feldspar and mica minerals, creating a smooth gliding sensation.

Historically, it’s akin to replacing the konbu (kelp) used to slide heavy stones for Osaka Castle’s walls with crushed flakes.

Excessive pressure when sharpening with too many unbroken flakes can create shallow scratches on softer metals due to the overlapping flakes and the strong sharpening power originating from Yamashiro Province.

Adjusting the pressure, sharpening angle, slurry amount, and water supply will improve your technique and reduce these shallow scratches.

The visible results make it easy to self-assess and improve your skills, making it recommended.

Experienced flake users will likely discover that the aforementioned konbu attack is very helpful when dealing with stubborn or hard stones that are difficult to sharpen.

It may rekindle your motivation to re-challenge previously abandoned or shelved hard stones. Ultimately, removing unruly grain through forging is the domain of master whetstone artisans….

The market tends towards shortcuts in manufacturing, prioritizing thickness and size for higher profit margins. Therefore, you may find opportunities to use the soft, reddish-pink slurry.

・Includes one finished 325g whetstone. Size is based on the outer dimensions of the box. One piece, including the outer box and rough stone, weighs 822g. These are whetstones from Iyo Province and the upper-class mines of Yamashiro Province, with the miner personally hand-writing the name to prevent counterfeiting and mislabeling. The forging marks shown in the image are sealed in the margin. The original stone does not have a name written on it, so please touch and judge the physical properties yourself. This is geared towards those with a competitive and training-oriented mindset. ・Neutral and rust-resistant whetstone from Tangawa Village, Iyo Province, dating back to the Edo period, revived after half a century!! https://bit.ly/IyoMIkantsubu The outer dimensions of a 10-stone box of Higo-ori (approximately): 13.5 x 18 x 4.0~7.8 cm. Thickness varies. (It actually overflows and bulges.) Total weight including the box is approximately 822g. We have eliminated the gacha element that many have requested. You will receive the stone as shown in the picture. ・Please polish the forging marks to create a flat surface. If it doesn't sit well, apply a wet cloth or secure it with silicone adhesive to a non-deformable base. Mining is done with heavy machinery, and cutting is done with diamond tombstone cutters. Regarding the “Iyo Meito” whetstones, we are not involved with products that have been falsely branded or have had names added without authorization. “Iyo Meito” whetstones since around 2007 have been made only from sazaire (small fragment) whetstones. All other names are handwritten to distinguish them. We cannot answer inquiries about “Iyo Meito” stones that have been selected and manufactured by others. ・Siliceous shale from Umegehata, Ukyo Ward, Kyoto City, Yamashiro Province. #6,000~24,000 grit. It requires some skill as it is harder, but it is more likely to become refined. Due to the continuous circular striations, it is difficult to achieve a mirror finish with 70% retention and an artificial whetstone grit ratio, making it easier to highlight forging lines, material differences, and carbon content variations. ・The harder the stone and the more refined it is, the more it resembles black rock juice. Because hardness reduces self-sharpening, perform regular 共名倉掛け (Kyomeikuragake – a specific sharpening technique) according to your purpose and skill level.

【Voltage Compatibility】 When using electrical appliances, please note that they are designed for Japanese voltage specifications (90-110V), so if you use them with a different voltage, it may cause a malfunction.

【Plug Type】 Our products use Japanese plug types (A or B type). Please use a conversion adapter if necessary.

【Important Note on Transformers and Adapters】 A transformer adjusts voltage to match your device's requirements. A conversion adapter only changes the plug shape and does not adjust voltage. Using only a conversion adapter without a transformer may result in damage to the product.

【Liability】 We are not responsible for malfunctions or damages caused by improper use, such as operating the product without a transformer.