Light Novel Volume 13

Issei SOS is the thirteenth novel of the High School DxD series. It is the first novel of the Legend of Oppai Dragon and his Lively Companions arc, and the second short story collection in the series, after Volume 8.

There are two editions of the novel published: a limited edition (released on September 6, 2012, of which 1000 copies were produced) which features an OVA 13th episode of the High School DxD anime on Blu-ray disc, and a regular edition (released on September 20, 2012) which lacks the episode. The episode was written by Ichiei Ishibumi, the author of the light novels, himself.

The Disturbance of a Devil
(Takes place after Volume 7)

The Unresurrected Phoenix
(Takes place after Volume 9)

Ravel Phenex comes to see Rias and Issei to see if they can help her brother Riser, who has become a recluse since Issei defeated him in Volume 2. The group agrees and they go to visit Riser, who they discover has become dracophobic (having an intense fear of Dragons) because of Issei at his family home in the Underworld. They drag him out of his room to where Tannin waited, and then Tannin took Riser, Ravel, and Issei to his territory, where he had trained Issei earlier.

In Tannin's territory, they encounter Riser's peerage and a large number of Dragons who serve Tannin. They force Riser to train, and Issei is told to train as well. Issei finds the training somewhat difficult, being unfamiliar with running in deep snow, but Riser is completely exhausted early into the first day.

After some time passes, Riser sneaks out to see Rias and Akeno while they are relaxing in the hot springs, hoping to get a peek at their breasts. Issei goes into Balance Breaker and chases after him. After a fierce battle, Riser is knocked unconcious, and Issei accidentally sees Ravel nude, which causes her to attack him with fire.

Riser is revealed to have recovered, but still have the hots for Rias.

Chapters

 * Life.1: "A Tokusatsu Devil"
 * Life.2: "Issei SOS"
 * Life.3: "The Disturbance of a Devil"
 * Life.4: "The Unresurrected Phoenix"
 * Life.5: "Armageddon at Sports Day!"
 * Extra Life.: "The Worries of the Next-Next Heir"
 * Afterwords