MAJO TO RYOUKEN

Amelia, a kingdom of war and magic led by Queen Amelia, monopolizes the supernatural power of "magic" and repeatedly invades other countries in a time of war. If things go on like this, Campus Fellows will perish. For the sake of the country's survival, the lord "Bud Grace" decides to take a devious measure by recruiting into his ranks a group of vicious "Witches" who are known as "Calamity" and have left behind many horrifying anecdotes. Raised as an assassin, "Black Hound," who has been trained in all kinds of assassination techniques, the boy throws himself into an impossible and bizarre plan to protect his country and his master. — Description from AniList community (anilist.co).