What is Tokushu Hagane?

[Stopper37]

I have recently came across a Gunto signed Tokushu-ko motte Ido Hidetoshi saku (特殊鋼以井戸秀俊作), while Guntos are usually not my cup of tea, I am very curious about what "Special Steel"/Tokushu Hagane is..... Kaigunto type rust resistant steel? Yasuki Hagane? Something totally different?

[PNSSHOGUN]

We would need pictures of the blade to determine anything of use. Special steels ranged from western iron, formulated high purity steels by various companies to self made steel or normal Tamahagane mixed with old steel from shrine buildings or other esoteric sources.

[Stopper37]

I didn't buy the sword, just saw it on a local gun sale site (I lurk those sites to find older blades in Gunto mounts). Generally I would go meh, it's showato but have never come across Tokushu Hagane on the tang before and curious about it.

 

https://www.buyusedguns.com.au/Japanese-sword-15712.html

[PNSSHOGUN]

The tsuba is a replacement but otherwise an interesting piece, especially for that price.

[Ganko]

There is a similarly marked one in Slough's book on page 33, Ido Hidetoshi

[Dave R]

 A quick google took me here...  https://www.tokkin.com/materials/special_steel/special_steel    so I think your Tokushu Hagane is simply this firms sword steel during the war.

[SteveM]

Here's another Ido Hidetoshi sword made from "Special Steel". It says the steel was developed from research carried out in the steel-producing town of Yasuki in Shimane prefecture. And, as you speculated, it is of the non-rust type, but it seems to be different from the stainless steel blades of the navy. 

 

http://www.nipponto.co.jp/swords3/KT324551.htm

[Stopper37]

Thanks guys.... Interesting, another one of those non tamahagane swords papered and sold in Japan... Anything is possible I guess... looking at the link, If it were rust resistant it really has much more nie nioi activities than the normal kai Guntos rust resistant steel... Maybe I should buy the sword..... No I must resist....