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.