After successfully rescuing his master, Rias Gremory, from the Dimensional Gap, Issei Hyoudou, the Red Dragon Emperor and aspiring Harem King, is excited to get back to his high school life with his fellow Occult Research Club members - Yuuto Kiba, Asia Argento, Xenovia Quarta, and Irina Shidou. The group plans a school trip to Kyoto and visits a temple, which is rudely interrupted by a hostile group of local youkai. Once the chaos dies down, the club discovers that the legendary nine-tailed fox, guardian of the city, has been kidnapped and they have been set up for the crime. This leads Issei and his friends on a mission to clear their names and save the city from disaster. As Issei and his crew embark on this journey, Rias is left behind in Tokyo with Akeno Himejima and Koneko Toujou. As she eagerly awaits Issei's return, Rias struggles to confront the intense feelings that have been building up inside her for months.