The good luck flag is obviously a fake or souvenir made after the war. The signatures, slogans and a poem were written by the same hand, and one of the signatures is a famous actor 大河内傳次郎 Ōkōchi Denjirō. There are two common patriotic slogans 祈武運長久 "eternal good luck in battle" and 忠孝 "loyalty and filial piety", but it cannot happen that a slogan "friendship between Japan and the U.S." is written on a good luck flag.
Also, there is a poem 人はさくら木 花は武士 on the right end, but this should be 花はさくら木 人は武士, i.e., "the best of all flowers is cherry blossoms, the best of all people is samurai". What's written there means "the best of all people is cherry blossoms, the best of all flowers is samurai".
There is an old address 東京都京橋区八丁目十六番地 on the left end of the flag. 東京都京橋区 "Kyōbashi ward, Tokyo", is the present 東京都中央区 "Chūō ward, Tokyo", but the address 京橋区八丁目十六番地 "8-16 Kyōbashi ward" didn't exist.
As for the second picture, 新妻鏡 Niizuma-kagami is the title of a novel/movie, so it might be a scene of it.