While Crunchyroll is primarily a streaming service, its premium tier ($7.99/month) allows offline downloads on the mobile app. You don't own the files, but you can store them locally for 30-60 days.

High School DxD is one of the most famous examples of the "Ecchi" genre, blending intense supernatural action with bold romantic comedy. Since its debut as a light novel by Ichiei Ishibumi

Many torrent batches labeled "Complete Series" only contain 4 seasons but miss the OVAs. Season 3 BorN has episodes 13 (OG) and 14 (OG) that are often mislabeled as Season 4. Always cross-reference with MyAnimeList (MAL).