Hi Volker,
I was also thinking of Tsuguhiro.
Just by comparing the following blade at uniquejapan.com. It shows a lot of similarities.
https://new.uniqueja...tsuguhiro-wakizashi/
I'm by far an expert and maybe other members can jump in.
Regards, Ed
The curved tsuka is in line with the curve of the blade. Gives it a pleasant look.
And because we militaria collectors like details a picture of the centered release button.