I'm here on a retainer, so let's get to work.

It's a list of names, from what I can read. From left to right on the legible kanji:
Sesikei : I cannot write this kanji in my IME because that kanji is so ancient it isn't even supported by windows. What this kanji means is "honesty", but I believe it means "oracle" in this case. Someone probably earned the nickname "Sesikei" by his troop or unit and signed the flag as such.
三上清喜 Mikami Seiki
正(cannot read)若人 Masa(...) Wakoto
志度雅夫 Shido Masao
The rest is ancient kanji and/or completely unreadable to me.
まほ~