Welcome to the forum, Greg.
There seem few clues to ID details but this flag was given to 中野勝巳 (Mr Nakano, Katsumi) as you would read it on the third line from the right.
His first name includes a letter "巳 (mi)" which means "birth year of snake" of the twelve horary signs.
The last snake year for his birth was 1917.
At the time, Japanese healthy men were enlisted in the army, if not volunteered to the navy, at age of 20 (19 from 1944).
He was to be enlisted in 1937.
Second Sino-Japanese War broke out in the same year.
He would have been sent to the front in China and, then, transferred to Guadalcanal in 1942 to leave the flag.