第 4 集: 圖書館解說世界歷史，隱藏危機悄然浮現
2012年10月20日 播出
As the library continues to explain the history of the world, a danger looms in the background. (Source: Crunchyroll)
As the library continues to explain the history of the world, a danger looms in the background. (Source: Crunchyroll)