Sorry mate, this is one of the fake flags that have been circulating around the internet (you can see examples on this site and others). The 4 largish characters should be on the top of the flag, and they read 武運長久. Good luck in battle, basically. The other scribblings are supposed to be names, but the names on your flag all look like they were done by the same hand, and some are repetitions. See the sticky post related to WWII flags and you will get more info.