I've been 'brain storming'
this blade and may have a solution to the questions that this sword isn't 'quite right' . During Japanese occupation swords were produced using local smiths....perhaps this is one.
I am thinking that a smith with the skill of producing Dha could have made katana's for the army using local techniques. I'm not certain but, the blade could have an inserted edge....the 'peaked' spine is not unusual to Dha and the thinner blade 3mm+ is also well known. As I said before the blade is faily good quality and appears to have a few cold shuts and therefore forged.
Any thoughts
Kind Regards David