Arc-en-ciel (アルカンシェル Arukanshieru) is the most powerful and, apparently, only weapon carried by the TSAB investigative vessel Arthra, as well as by many other TSAB ships. It is a "magic cannon" (魔導砲 madōhō) capable of destroying everything withing a 100 km radius of the target point by distorting the time-space of that region. Because of its great destructive potential, it can only be fired with the ship captain's key.