It looks like some parted together fantasy creation (like Grandpa got bored in the shed one day). The crosspiece/muzzle ring looks like it has been “repurposed” from a Swiss military SIG PE57 bayonet (see below picture from this website MyBlades – knife showcase blog » Swiss military SIG PE57 bayonet) as such, it is definitely not something that left a Japanese military factory. I’d hesitate to call this a bayonet as it does not appear to have any mortised slot for fixing it onto a weapon. I would not call it a "theater made" knife either (unless we are talking Vietnam?) as it is made from post-WW2 bits; I have no idea on the blade’s origin as it does not appear to look like any of my Japanese bayonets’ blades. I’d keep walking if I saw this offered at a flea market. Just my 2Cts.