The Empress and Her Time-Traveling Fiancé

Evan Holt time-travels to the world of Sora and finds himself as the son of Duke Holt in Cloudin. Bound by a marriage pact with the Empress, he is unwilling to go through with it. To avoid the marriage, he pretends to be a useless brat for three years, all the while secretly developing powerful weapons. Eventually, the Empress, fed up with his charade, calls off the engagement.