He entered First High School together with his younger sister Miyuki and excels at written exams and magic engineering. His knowledge and technical prowess surpass that of any ordinary high school student, but he did poorly on his practical skills exam, which is why he was labeled an “irregular student” and placed in Course 2. He is the eldest son of the Yotsuba family, which is one of the Ten Master Clans, and has the ability to use Strategic-Class magic such as Regrowth and Material Burst. Due to the side effects of an experiment that he underwent, he has lost most of his emotions, but his deep love for Miyuki still remains. He can sometimes seem aloof and quiet, and has a hard time understanding the feelings of women.