Katana original ?
 

I cant rekove handle

It's a WWII shin gunto (sometimes they have older blades but hard to say). I know there are some fakes out there but I'm not very well versed in them, though fwiw I don't see anything suspicious.

Hi,
Just add DW40 above the guard, shake up and down the hilt and press the silver button on the fushi.
Normally you will be able to remove the tsuka.
Best wishes,

finally managed to remove the handle.

Definitely original.
Never clean the handle/nakago, aside of some oil/wd40 and gentle rubbing with a cloth.

Chek the blade with japanese sword expert, i think it is not old blade but made in period of mountings, by some blade smith, maybe for general? It has file marks but they are crude, and it has stamp partialy seen under habaki, im 90% sure it is not nihonto.

Get it examined with expert for japanese swords, it is finely made, it could be valuable.
Signature is done on made, not adition.

Nakago=Tang
 

aspalathos,

Pieje is correct. Never clean the tang beyond a bit of WD40 and a soft cloth. I advise you to check out the Nihonto Message Board forum for full advice on the care and feeding of Japanese swords. It is a world unto itself and if you don't know what to do, you can make a grave error that will damage your piece and significantly erode its value. Your blade has a signature which means that it is at least a cut above the entirely factory made blades. Someone on the message board will be able to translate the signature.

Sincerely,
RobT

I agree with everyone. Might be a traditionally made blade, but not ancestral.

Hi and thanks to all. What I find strange is that the tang only has one hole.

That is very common. As already recommended, the NMB will likely give you the assistance you need.. They were very helpful about a nihonto of mine there and were incredibly swift and knowledgable. Japanese swords is a world of its own, just like keris. They have decades of research ahead of you, ask the experts :)

Nihonto Forum
 

They have a specific translation section... wasn't sure if a link was allowed! Be sure to post a picture of the Mei (the sword signature... those japanese signs hidden under the handle) there, but right way up :)

The link can be allowed if it is not to something involving selling/buying.

Gentlemen, thank you very much, it's great to be a member of this forum. There are wonderful and patient people who are always there to help.
Thanks !!!

Nevr-Dull
 

aspalathos,

One other thing I should have mentioned, The NMB members seem to be ok with using Nevr-Dull to kill live rust on the blade if necessary. Don't use it on the tang of course but you can use it on the blade.

Sincerely,
RobT

Your blade looks to have two stamps, Sho and Seki, so it is non traditional in some way and made in one of the workshops of Seki City. Non traditional covers a lot of different things, and having a signature means it was hand forged, not "Machine made".

Hello, friend,
This is a typical Japanese military sword from World War II. I have translated the inscription on the hilt and marked it in the picture. I hope you can understand it. The character in the plum blossom emblem is '昭', and the others are.濃州住大矢友信. I hope this helps you.Attachment 250686