Thread: What kind of knife is this?

I know we have a lot of cutlery fans around here, so I thought maybe one of youns would know...

I ran across this knife posted on a Japanese auction site, and it has me really intrigued. The seller says that it's an old family item, and they have no idea what it's supposed to be used for, but that it's frighteningly sharp (the listing is "Knife/Razor/Scalpel...) It's 19.9cm long, the blade is 14.5cmx3.4cm

Any ideas? It looks...interesting.