Too hard to say. They are mostly just names on the first two. First one is addressed to a Mr. Kobayashi, and second one is addressed to a Mr. Ota. Not too much more information other than that. Its nice to have a lot of detail on the flag giving us clues as to who the owner was, as that helps establish authenticity. But its not any kind of hard requirement, and indeed many flags just have names on them, like these two flags. The third flag is a bit more interesting in that it has the name of a specific battalion, which could validate its authenticity. So I'm indifferent as to the first two, and slightly positive as to the last one.
Note that many flags are almost instantly recognizable as fakes because of the phony writing on them. The writing on your flags all seems legitimate, so that's a positive thing. Just not enough info to say with any certainty.