This is the first game of a six part series covering all the flags of the Japanese prefectures. Please note that this game uses only the English names of the prefectures and not the native Japanese names.
Hiroshima: By "Alex Tora" [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)] URL: https://commons.wikimedia.org/wiki/File:Flag_of_Hiroshima_Prefecture.svg
All other flag images under public domain and obtained via Wikipedia/Wikimedia Commons.
Good Luck :)