A special story distributed with the BorN Blu-rays that offers a glimpse into a potential future involving Issei and the heroines' children. Season 4 ( Hero ) Extras
If you're watching for the , most of the short specials can be skipped as they are purely for comedy. However, the full-length OVAs and the Hero: Taiikukan-ura no Holy special are highly recommended. The latter is especially critical for those confused by the changes made during Season 3, as it helps bridge the gap to the more faithful Season 4 adaptation. How To Watch High School DxD in The Right Order! High School DxD Specials
These are 3–5 minute shorts bundled with the original Japanese DVD/BD releases. They are mostly standalone comedic skits with no impact on the main plot. Season 2 ( New ) Extras A special story distributed with the BorN Blu-rays
These two full-length episodes follow the first season. One focuses on a vacation to the beach—which ends with Issei in typical trouble—while the other deals with a "breast-shrinking" rumor at school. The latter is especially critical for those confused
Bundled with DxD DX.2 , this episode follows the BorN season.
Bundled with the Hero Blu-ray, this provides the origin story of how Sirzechs and Grayfia met during the Underworld's civil war. The "Must-Watch" Verdict