The Outside Reason (外の理 Soto no Kotowari?) is an unknown transcendental force that only the Ouroboros Grandmaster can harness in the Kiseki universe. Details still yet unknown, only the grandmaster can bestow the power to anybody deemed worthy, enabling to materialize a weapon on par or exceed the Sept-Terrions.
- George Weissmann's staff
- McBurn's demon sword "Angue-Barl (アングバール, angubaaru)".
- Leonhardt's demon sword "Kernviter (ケルンバイター, kerunbaitaa)".
- By all definitions, it means "logic/reason/truth of the outside/other place"
- In another meaning, it is a hypothetical logic or set of alien laws of physics existing 'outside' of the material world.