High School DxD Hero

After returning from the Dimensional Gap, Issei Hyoudou joins his classmates on a school trip to Kyoto without Rias, Akeno, or Koneko. What should be a brief vacation becomes a crisis when local youkai attack them, followed by the discovery that Kyoto's nine-tailed fox guardian has been abducted and the Occult Research Club has been framed for the crime.

Issei and the others must rescue the guardian and stop a disaster targeting the city while separated from some of their strongest allies. Back in Tokyo, Rias can no longer ignore the anxiety and jealousy stirred by Issei's absence. Between the battle and a relationship that has been growing more complicated for months, both are pushed toward feelings their usual jokes can no longer hide.