Actually, most of them don’t even have one in the source material.
Summary:
- Even people who like isekai anime complain about them never having a proper finale.
- Most of the time they only exist to promote the source material.
- We might get full adaptations for anime like Mushoku Tensei and KonoSuba.
Isekai is a controversial genre among anime fans. They’re criticized for many reasons: being wish-fulfillment power fantasy, generic settings and protagonists and over-reliance on fanservice. Still, the genre has its fair share of fans… but one of its main flaws is noticed by the fans as well.
Regardless of the actual content of modern isekai series, they all have something in common. They seem to never end properly — at best, they conclude an arc. Still, a lack of proper finale for the series is occasionally brought up in discussions about the genre — and the reason for that is how the industry works these days.
Adaptations Only Promote the LNs
While the idea that “anime is just an advertisement for its own source material” is a misconception, there is a grain of truth to it. The success of the anime and its source material is very much related.
Moreover, the light novels which most modern isekai are based on tend to run for many volumes — usually over 10. The anime come out when they’re still relevant — when they’re still ongoing — and only adapt the first few of them.
Meanwhile, the publishers often make the authors write more and more volumes until sales dwindle — essentially making the light novel irrelevant after it finishes. As such, there’s no financial incentive to adapt it further.
Isekai Anime Often Have Poor Sales
Most isekai anime don’t really sell that well either. On average, they just boost the attention towards the source material — and maybe for the manga adaptation of the same LN. The actual sales for the BDs tend to be not that high, and the TV ratings don’t help either — it’s not always profitable to give the anime another season.
We May Get Some Full Adaptations of Isekai Series
While in the past, isekai anime tended to actually conclude — InuYasha is a good example — we shouldn’t really compare older isekai series to the modern take on the genre. After all, isekai wasn’t tied to light novels back in the day.
There are also examples of long-running (multi-season) modern isekai anime. Perhaps the most famous are Re:ZERO -Starting Life in Another World- (Re:Zero kara Hajimeru Isekai Seikatsu) and Mushoku Tensei: Jobless Reincarnation (Mushoku Tensei: Isekai Ittara Honki Dasu).
The staff behind the latter has expressed the wish to adapt the entire series — and the source material is actually finished. While Re:Zero is still ongoing, fans believe it’ll get that treatment as well.