Isekai is a blend of kawaii and harem anime
Many iSEKAI aNIME protagonists are young or in their teens, which is part of the appeal in itself. A lot of people like to think that isekai shows feature characters who are transported to another world (and thus bring along their skills and memories with them).
However, there’s always something off about these heroes when they first arrive in this new world. For example, they might be even more incompetent than they were in their old lives due to not knowing anything about how the world works; or maybe they’re super weak (e.g., looking like an average high school student), but usually not too dumb (so it doesn’t feel like they don’t deserve to be there).
It can work out in a show’s favor when the protagonist is pretty good at something upon arriving in the new world, like Sayaka Miki who had some talent for music, and Kyosuke Kamijou (A Certain Magical Index) who was smart and athletic. However, some anime make these characters completely useless or even sickly or weak initially; this kind of protagonist will either rise to greatness through training and determination or remain pathetic while some other force somehow makes him useful later on.
In all cases, they need a reason to stay rather than want to return home because this is their chance at a fresh new life away from whatever problems they might have had before. Another point worth mentioning is that most of the time only one person is transported and it’s usually a guy who ends up alone. For some reason, the female protagonist is never transported along with him (or vice versa).
Isekai anime exists to sell merchandise and promote other works
When we think of isekai anime, we often imagine worlds full of magic or technology where people live in peace without laws or obligations governing their behaviour outside of what they impose upon themselves. While this might be true for many isekai shows, it’s important to remember that these stories are also made to promote existing properties by using their characters as well as advertise products and entertainment and even political agendas and points of view (e.g., Pokemon: The Origin). if not all commercially successful franchises need to have at least one isekai series.
Isekai anime is targeted at kids and teens
Isekai anime don’t just appear in shows made for children and airing on Saturday mornings. Anime like Re: Zero and Overlord can be enjoyed by adults as well, and many of these stories contain dark themes that would not be appropriate for younger audiences (e.g., violence, rape, cannibalism). Additionally, some anime adapt light novels aimed at young men or boys which means the protagonist might get romantically involved with someone he meets in the new world (usually a girl), but even if it’s never explicitly stated it might still happen because we can’t forget about all those important beach scenes! This is why isekai anime is often thought of like a harem (a series with one guy and many girls) or a reverse harem (one girl and many guys). Of course, isekai isn’t the only genre to feature such tropes.
Something else worth mentioning: some isekai anime don’t take place in traditional fantasy worlds like those found in fairy tales and classic literature (e.g., Dungeons and Dragons, Lord of the Rings), but rather worlds where magic or technology has taken over; this kind of world building tends to be more modern and relatable to certain audiences who embrace science fiction as part of their everyday lives. It’s also important to know that not all isekai characters are transported from our world as we might assume, but rather from their world into another.