[Excessum]

Originally Posted by Sangetsu

It's not a shin-gunto, or anything of the like (I've owned several). The only thing resembling a WW2 Shin-gunto sword is the handguard, and the lanyard ring at the end of the hilt. Shin-gunto swords never came with wooden scabbards.

In the first picture the temper line is obvious, and I can make out that the steel is laminated. Shin-gunto swords were not laminated, nor were they tempered, the blades were stamped out of the same material as railroad rails.

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Here are a few easy ways to spot a shin-gunto sword. First is the materials. Shin-gunto swords come with steel scabbards (painted green), with the end stamped flat. The hilt will be made of cast aluminum (usually, some were made of copper, and a handful were made of patterned wood), with an embossed pattern resembling traditional cord wrapping, and there will be locking catch which must be pressed before the blade can be drawn.

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Tsk, tsk, tsk... i think you are fogetting the fact that there were several models of shin gunto made. What you described here is the regular type 94. While the late type 95 and most of the type 98 swords would come with a wooden scabbard and brass, or steel ornamentation. I have also had my arms on a (ok, i've never owned one, I have to admit) couple of shin guntos's. One of them was a Type 95 and you can immediately tell the difference between those two. Type 95, unlike the 94, features a blood groove and stenciled text/numbers on the blade, tsuka, tsuba and habaki are made out of copper, the kissaki is at a different angle and other minor differences and they were issued to the officers in army reserves (unlike type 94, that were given to officers that were in active service).
Type 98, were a over-simplified version of the 94. They introduced a wooden scabbard and on the later models tsuka was also made from wood, however, saya still sports metallic kojiri and koiguchi, as well as a metallic base of the mounting space. The fact that the blade is oiled, does not mean it was oiled straight out of the factory (though I am unaware about the protection for the blades they applied for these swords, if any).
Well, the bottom line is that it could, theoretically, be a kai gunto... I don't know much about them though and I really don't see any other alternatives... The pre-WW2 army swords did not look like a katana and were made with much more detail... so unless it is some bizzare custom-made sword, I am sticking with the opinion that it's a Type 98 shin gunto.