Everyone should just stay away from manga and anime. So much, if not absolutely most of it is immoral filth. Juvenile stories told with immoral themes and aimed at teenagers. Fantranslations make the stories impossible to regulate and many children are subjected to stories they should never have seen, let alone anyone of any age should see. They are not only ugly in appearance and telling, but ugly in their morals and intent. I pray that the whole phenomenon dies away insha'Allah.
I have no interest in them myself but I think that if Muslims get invovled with the genre and contribute wholesome alternatives to it, then it can be reformed. For example I grew up watching Arabic-dubbed anime on the popular SpaceToon channel and there was nothing in that except good moral teachings, besides the entertainment and fantasy.
If just leave the genre alone then that would just increase the chances of our teenagers going to the unwholesome versions of it. So I believe the first step toward a solution would be an English-language alternative to SpaceToon that only presents the wholesome animes.
I do agree with anime and manga having a good moral teachings in it. I do aware that most anime nowadays are full of obscenity (what we call fanservice) and I truly have no idea why the creators do that. In my opinion, without adding obscenity, anime and manga are a pretty descent consumption for all ages, just cast aside the bad elements in it (usually it only has a tad bit amount of fanservice).
I myself, grow up by watching anime and reading manga, but I always turn away every time there is any obscenity or bad elements in it. It depends on the kids/teenagers, too. I mean, some of them may not stand the intensity of the anime/manga, be it being too scary, gore-y, absurd, etc.
But I do not rule out that some people will look at it in a weird way. Japan has this knack of making a bizarre and uncanny art, storyline/plot, or character design whether it’s done for the sake of creativity. I haven’t watched anime again half-end to my university life, just because they have obscenity in it. I wouldn’t risk to watch it just because.
Old anime/manga has a very admirable moral teachings and shows that Japan has a good side to them too, while a more modern anime/manga moral teaching is slightly faded away.