Looks like a "last-ditch" type 38 Arisaka to me, but the early sight is odd. The "last ditch" rifles are some of the worst rifles ever made, ABSOLUTELY under NO circumstances should you fire this rifle, reduced pressure charges aren't safe either.
Basically, in 1945 the Japanese government KNEW that sooner or later, America would have to invade the Home Islands to end the war. Their principal arsenals were high on the target list, so they dispersed their armament manufacturers. Basically, if you had a shop with any metal working tools, you got put to work making rifles, pistols, or machine guns. You can imagine the results when people who have never even held, let alone USED a rifle, suddenly have to MAKE one. Substandard steel, hand-filing instead of machining, tolerances along the lines of "Eh, looks close, toss it in the crate!"....