Issei Hyoudou, the high school student with a desire for a harem empire and a lustful nature, continues to cause trouble in High School DxD New. Even Yuuto Kiba, typically calm and observant, is acting peculiar during their Exhibition Research Club activities. Issei discovers Kiba's past of torment and violence inflicted by the enigmatic Holy Swords, leading Kiba on a quest for revenge. At the same time, a previous adversary is back on the scene, and two beautiful women wielding the Holy Swords make an appearance, throwing Issei and his demon cohorts into a complicated maze of secrets and plots.