Spike dagger. Japanese?

[AHite]

I just acquired this interesting spike dagger. Due to markings on the blade, I am thinking this could be Japanese in origin but am open to opinions or comments. Overall, it is around 24 inches long. The sheath and handle are covered in leather (possibly eel skin?) and have very nice and fine stitching along the seams. The leather has what is left of a glossy finish, possibly lacquer. The sheath has a wood core, and probably the handle. The blade is four sided, and is obviously handmade. One two sides are three markings, which look Asian in origin.

Being a spike dagger, this was most likely a weapon. Not much use for it otherwise unless to spike a cannon! There are two brass nails located at the top of the sheath, and I believe these may have held some piece that would allow the sheath to be connected to a belt, or what ever. The piece seems to have some age to it. Again, any comments or opinions are appreciated!