Back in the day, it seemed to be the most popular ecchi anime.
Summary:
- High School DxD was extremely popular in the past, but no one talks about it now.
- S3 went in an anime-original direction, and S4 went back to adapting the LNs — but it had a lot of other problems.
- Because of the poor reception of S4, it's unlikely to get adapted further.
It feels like less than a decade ago, High School DxD has been one of the most recommended ecchi anime out there. Even those who didn't like ecchi often praised the show, citing its engaging story and an actually interesting protagonist.
However, over the years, it feels like the hype has died down. At this point, no one's talking about the series anymore — outside of the very devoted fans who still hold hopes for Season 5. It coming out is unlikely, though — the anime lost its popularity for a combination of reasons.
The Problems Started with Season 3
The anime was actually pretty successful with its original three seasons, but there was a huge problem. The third season, BorN, had a more polarizing reception than the first two, and it only got worse over time. The reason for that is simple: roughly half of S3 is anime-original, straying far from the light novel storyline.
This led to another problem. After a season which heavily changed the storyline, the anime couldn't really continue — it would need an entirely new story. This would essentially make it not an adaptation at all, and it's likely that the publisher didn't want to invest into it.
Fans Disliked Season 4
That said, we actually got S4, DxD Hero, a few years after S3 was released. It went back to adapting the light novels, and was made by Studio Passione — while the first seasons were made by TNK.
The fourth season ran into another problem. While it went back to adapting the LNs, it also had to recap the events S3 skipped, which it did in Episode 0. However, many fans weren't even aware Episode 0 existed, which made them very confused.
Another reason why S4 was looked down on was the art style change. Notably, when the studio changed, so did the art.
While fans often tend to overreact to these changes, it's hard to blame them here, as they were used to a different art style used in the first three seasons. Besides, the animation quality took a nosedive as well.
Why It Won't Get a Sequel
It's very unlikely that DxD will ever get a sequel. After all, the trend for battle magic school harems is practically dead now. The reception of the fourth season was less than stellar, to say the least.
Besides, Passione isn't a studio known for multiple-cour productions: most of their anime only have one season, which is only one cour long.