VG-10 is high-carbon stainless steel containing cobalt hard. The material has excellent sharpness and abrasion resistance. So it spread between the professionals. It is developed and made by Takefu Special Steel Co.,Ltd.  It's Japanese company.

If the entire blade is very hard it is difficult to sharpen. If the edge is soft it is dull and the sharpness falls immediately. So the hard material is used in the core edge only the soft material is used in the side.  VG-10 is hard so Ceramic sharpening stone is recommended for speedy sharpening.

Type: Boning Knife / Honesuki (Single Bevel For Right Handed)
Blade Material: DP Cobalt Alloy Steel Clad Material
Core: Cobalt Alloy Steel (VG10)
Outside: 13 Chrome Stainless Steel
Blade Length: 150 mm (5.9'')
Total Length: 275 mm (10.8'') 
Thickness of Spine: approx max 3 mmWeight: 170 g (6 oz)
Handle: Special Laminated Material
Made in Japan