Thank you for your explanation. I have also seen that sword on Yahoo, and like my sword, the blade has no markings. Apart from that, I haven't found a third sword of the same model. I appreciate the information you provided. I suspect that this sword might be a royal gift sword gunto presented by the Army University during the late Meiji or early Taisho period. Regarding heat treatment, I am also puzzled. It seems that there was no heat treatment involved.
Sam