Japanese blade

[Miguel]

I agree with Kai regarding condition and would certainly try the electrolysis process to remove the rust. I have found it to work very well. If you don't know about this process google rust removal by electrolysis which will tell you what you all you want to know. If you wish to bring it back to its original polished condition it will cost you several thousand pounds.
Miguel

[RobertGuy]

In the close up of the habaki it looks as though the blade lower edge at the hamachi runs into a slot in the habaki rather than being coned by it and resting on the machigane inside the habaki. Not conclusive but does point to a non traditional Japanese blade.