Ian,
Sorry for the delayed response. I am not 100% sure, but I did find that the following smith, who was registered in Seki. Please see the below reference from Markus Sesko’s Swordsmiths of Japan:
KUNIHIRO (国広), Shōwa (昭和, 1926-1989), Gifu – “Kunihiro” (国広), real name Kataoka Itoshi (片岡愛), born am April 1st 1895, he worked as rikugun-jumei-tōshō and died December 2nd 1965, ryōkō no retsu (Akihide).
There were a few smiths who used the swordsmith name Kunihiro during WW2.