The Irregular at Magic High School - 1x18 - 九校戦編11- Followmy.tv

Tatsuya attacks a meeting of the No Head Dragon members by casting extremely long range magic from a tower visible from their meeting place. After learning that the head of the organization's name is Richard Sun, Tatsuya proceeds to kill everyone present at the meeting, mostly influenced by his feelings for his sister. On the next day, the competition ends with Jyumonji single-handedly winning the Monolith Code event, confirming the championship for First High School. After Mayumi and Jyumonji discuss the long-term effects that Tatsuya's victory over Masaki (the probable future head of the Ten Master Clans) as the reputation of the Ten Master Clans could be tarnished, Tatsuya is asked by Jyumonji to join the Ten Master Clans by marrying Mayumi or one of her sisters.