The isekai genre is more popular than ever, to the point that every anime fan knows what it's is about even if they haven't seen or read a single isekai series themselves. The isekai genre is a classic example of escapism, where a person in an ordinary (or miserable) life ends up in a fantasy realm with no rules and no limits. But perhaps this is a little too much freedom.
Although this genre is well-suited for escapism and even power fantasies for gamers, the problem is simple: how does the journey end? Many isekai series dodge this question entirely, or if they are ongoing, there is no clear indicator of an ultimate end goal or escape from the fantasy realm. This might hinder the narrative in many cases, even making it all feel pointless.
The Neverending Isekai Hero's Journey - Where's the Meaning In Forever?
It may be noted that while there is no right or wrong way to conclude an isekai anime, there may be hazards with having a totally open-ended story, especially if the genre is inundated with such narratives. Regardless of genre or theme, all stories must work their way to a clear conclusion where conflicts and problems are resolved one way or another, aside from a few ambiguous loose ends if the story calls for them. Still, the isekai genre sometimes plays fast and loose with this rule, and many isekai stories lack the material to even try and have a meaningful conclusion in the grand scheme of things.
Of course, such stories can have a main villain, such as a demon king or a corrupt nobleman, but defeating those foes typically won't bring the isekai hero back to their own world or give their new life any further meaning. Once the final boss is dead, the "game" keeps going forever, and the only option left is to grind and farm goodies just to fill the time. That's not much of an ending.
Such stories may end up concluding with the hero thinking, "I'm here forever, but I've made friends and had fun, so we'll see what the future brings!" Such stories don't have a solid conclusion; they just stop, which is not the same thing as an ending. Once in a while, this actually fits the narrative, such as with I've Been Killing Slimes for 300 Years and Maxed Out My Level, where the heroine, Azusa Aizawa, simply wants to relax while distancing herself from her original workaholic life.
Other isekai heroes with no clear escape or ending will simply occupy themselves with busy work for the benefit of the people around them, such as Rimuru Tempest, who (unlike Azusa) can't sit still for long. He's too busy playing "let's build a nation" to just goof off like that. That's reflects well on him, but it still doesn't provide a solid conclusion to the story. In fact, if the hero's life stretches on forever, then any victory they achieve over demon kings or evil dukes will ultimately feel trivial since it's just a tiny blip in an infinitely long isekai life. 3,000 years later, who will care if the evil duke was taken down? No one will even remember.
A Solid Conclusion to an Isekai Story Needs Clear Stakes
Easygoing series such as I've Been Killing Slimes can get away with a lack of a clear end goal since the entire point is to subvert the genre. Otherwise, isekai stories such as Sword Art Online usually benefit from having a definite goal to reach -- usually, escape from the fantasy realm to return to normal life (if possible). Not all isekai heroes actually enjoy their new lives and might have left behind all kinds of things from their original lives behind. So, the hero and the narrative alike are strongly driven by the promise of getting things back to normal. This can help keep the narrative tight and focused and allow all events and dialogue to flow in that direction, as well as prevent a series from being messy and feeling improvisational.
In Sword Art Online, Kirito, the hero, had to clear all 100 levels in Aincrad to escape the game, providing a solid goal upon which the story could rest, and when Kirito and Asuna succeeded, it was highly satisfying and cathartic. The Rising of the Shield Hero's Naofumi Iwatani, meanwhile, is promised that he may return home once he helps save the Melromarc Kingdom from all the Waves, giving him something to work towards, providing meaning in the action sequences. Some older, western 'isekai' stories do something like this too, such as 1939's The Wizard of Oz when Dorothy Gale dearly wanted to return home to her family, even though Oz was a much more colorful and fun place than Depression-era Kansas. She had that to drive her along, and defeating the Wicked Witch of the West was the main way to achieve that goal, aside from clicking the heels of those ruby slippers.
All this can help prevent the viewer (and even the hero) from wondering "where is all this going? What's the point?" That solid end goal is the point, and everything the hero says and does is purposeful since it leads them closer to that goal. No one wants to run a race with no finish line, after all. That's just a literal exercise in futility. Unless they are Azusa Aizawa, that is.