This knife is Interrupt Welding (Warikomi constraction) and forged by Satoshi Nakagawa 

This VG10 knife is our recommended knife.
Many famous Japanese cooks use this knife.
The reason is that it does not rust and its sharpness lasts for a long time.
Also, VG10 production does not require a blacksmith.
A sharpener cuts the steel and hardens it in an electric furnace.
When sharpening, use a diamond whetstone and finish with a natural whetstone
When used, it becomes a razor-like blade.

It is a practical kitchen knife that is fun to use every day.
We want a professional sushi chef to use it.

Material Details
When users choose cutting steels which are suitable for various kinds of knives,
their demands for the performance of cutting steels becomes diverse, but the
indispensable prerequisites of good steel has never changed.　
V Gold 10(VG10), a high quality cutting stainless steel, is made from highly-selected
pure iron material and is worked by best technology, thus VG10 has ductility and shows
orkability and forgeability. Besides VG10 is free from corrosion caused by impure substances
and achieves good abrasion resistance. Our V Steel Series boast these excellent features.

VG10 is a highly alloyed stainless cutlery steel, originally developed by Takefu Special Steels
over 60 years ago to make the most of quality raw materials and the alloying effects of various
element to make an all-round, high performance blade steel. The addition of 15% of Cr, 1% of Mo
and 1,5% of Co makes the matrix (substrate) stronger and prevents carbides from dropping out.
By adding V, the structure becomes finer.
Combined Cr, Mo, and V form a lot of hard carbides, so abrasion resistance improves which gives
knives long-term clean cutting, VG10 is rather machinable and easy to grind.

VG10 also has a quadratic effect in high-temperature tempering which makes it ideal to use in cutting
tools which are given surface-coating at up to about 450°C.

Excerpt from steel material manufacturer Takefu Special Steel Co., Ltd. HP