Aria the Scarlet Ammo season 1 episode 6
Episode title: Maiden of Hotogi Shrine
Shirayuki is revealed to be a Chōtei, a special type of Butei with esper abilities, as she conflicts with Aria, not helped by dubious misunderstandings. The next day, Aria decides to start a new training regime to try to get Kinji to control his Hysteria Mode. Later, Aria drags Kinji to eavesdrop on Shirayuki as she is taken to the teacher's office, hearing about a Chōtei kidnapper named Durandal who may be targeting her. Believing Durandal to be one of the culprits who framed her mother, Aria offers to be Shirayuki's bodyguard, which she agrees to on the condition that Kinji does so as well, moving into his house in the process.
