After successfully rescuing his master, Rias Gremory, from the Dimensional Gap, Red Dragon Emperor and aspiring Harem King Issei Hyoudou can finally return to his normal high school routine alongside Occult Research Club members Yuuto Kiba, Asia Argento, Xenovia Quarta, and Irina Shidou. The group embarks on a school trip to Kyoto, but their visit to a temple is disrupted by an assault from local youkai. Following the skirmish, the club learns that the mythical nine-tailed fox protecting the city has been abducted and that they are falsely accused of the crime. Issei and his friends must fight to clear their names, save the trip, and protect the city from impending disaster. Meanwhile, Rias, who stayed behind in Tokyo with Akeno Himejima and Koneko Toujou, grows increasingly uneasy about leaving the perverted Issei alone with the other club girls. Beneath her vague anxiety lies a deeper question: what are the true feelings Rias has been struggling with for the past few months?