That’s fine. The books were adapted as internationally distributed and translated movies and comics.
Both are set in alternate reality futures.
In Battle Royale, Japan won WWII.
And yet the victors of Battle Royale I still perpetrate a 9-11 type destruction of Western(? American?) skyscrapers at the opening of BRII and even escape to be with apparent Afghanis in the hills at the end of BRII.
So much for alternative futures.
By the time the second book came out SOMEONE must’ve brought it to her and the studio’s attention.