As a Knight, I Secretly Became the Devil

As the strongest knight, I became the Demon King! ? The flow of the heavens, decisive killing, sword and magic. The book title is also known as: "Wandering in the Heavens", "If you don't accept it, go and die", "Dominate the Heavens from Now on", "I didn't expect that I have two sets of armor", "Brother, your armor is not as good-looking as mine"