I am told it is: "Hizen-koku Yasunori"
To me, this horimono looks really beautiful. Then again, I can't even draw this well with pencil. I couldn't even imagine the kind of patience and talent it would take to carve this into steel, one millimeter at a time. I just wish I knew what the heck is happening in the image. Why is there a dragon climbing all over that ken? Sorry if that's a silly question. I know even less about Japanese mythology/symbolism than I do about swords.
Maybe with the proper polish, this sword would look really tremendous as a display piece.