Sukenari Blue 2 K-tip Yanagiba 270mm, Ebony Brass Handle

Yes, carbon steels such as Aogami (Blue) and Shirogami (White) are not stainless steels, so left wet they can spot or rust.

Care is simple once it becomes habit. Wipe the blade as you go, especially after acidic food like citrus, tomato or onion. When you finish, wash it in warm water with a little soap and dry it straight away with a towel. Do not let it air dry, leave it in the sink or the dish rack, or put it in the dishwasher. Store it dry: on a magnetic strip, in a saya or in a block in a dry spot.

If the knife will sit unused for a while, wipe on a thin layer of oil before storing. In our video James shows that mineral oil can stand in for camellia (tsubaki) oil, and he picks one labelled medical grade; we list the Kitchen Knife / Cutting Board Mineral Oil Medical Grade for this. If you find light rust, lift it with a rust eraser and a little water, then dry and oil the blade; we list the CKK and Naniwa rust erasers.

Proterial lists 1.05 to 1.15% carbon for both steels; its Blue 2 table lists 0.20 to 0.50% chromium and 1.00 to 1.50% tungsten, while its White 2 table lists neither.

Proterial describes White 2 as a carbon steel with minimum impurities and high hardness, and Blue 2 as an alloy steel with tungsten and chromium to improve heat-treatment properties and wear resistance, with a hardening hardness of over 60 HRC for both. In its Japanese materials, Proterial calls its Aogami (青紙) steels high-carbon steel (高炭素鋼). Neither steel is close to the JSSA's 10.5% minimum for stainless.

Sukenari's own site carries both names together, titled the official site of 株式会社スケナリ with 佑成 named as a registered trademark. 佑成 is the house mark that appears on the blades.

So one house answers to both names: Sukenari is the company, 株式会社スケナリ, working from Fuchu machi in Toyama City, and 佑成 is its mark on the steel.

Yes. Sukenari says its knives are made by craftsmen by hand, one at a time, at its workshop in Fuchu machi, Toyama City.

The Sukenari lines we stock carry the workshop name in their titles.

The workshop says the 佑 of its registered mark 佑成 (read Sukenari) is written with the person radical and 右, right, and that the character carries the wish for its tools to become the cook's indispensable right arm.

The company's own site title reads 登録商標 佑成 (registered trademark), and 佑成 is the house mark on its blades.