I'm not really happy, but thank you very much for the help.Unfortunately it seems to be a fake of the same kind that pop up here once or twice a year. The phrase at the top is 武運長久 (good luck in battle). The writing on the flag, however, appears to have been done by one person, who's thrown a few names and a few slogans on the flag at strange angles (along with a date of 1944) to try to make it look authentic.
I'm not really happy, but thank you very much for the help.
Are there more people who doubt the authenticity?