An academy has been started where the academy contains students with various powers, including wizards and knights, both nobles and ordinary students. Lucius is the son of the northern Grand Duke who rarely goes to the Academy because he always participates in wars with his father. This time Lucius entered the academy and while in the dormitory, Lucius shared a room with a man named Obsidian. On the other hand, Obsidian is a female figure but her identity is kept secret, no one knows, including Lucius himself, that Obsidian is a woman. except for teachers who know Obsidian's identity