Thanks for your answers and participation.
Vampire Hunter D was adapted into Pathfinder.
The world of "Record of Lodoss War" had got its own RPG.
Attack on Titan are awesome monsters, but a campaign with only those monsters would be boring.
The famous 80's D&D cartoon was ikesai, and we could say there is an canon ikesai in D&D. The children from Odiare, a dark domain in Ravenloft, are from Italy, but the setting "the mask of the red death". Urban Arcana was practically a reverse ikesai. Onyx Path wants to publish "Legendlore", a "Western ikesai".
Full Metal Alchemist could be a great source of inspiration, but those alchemist would need their own base clase, maybe something like the Vanguard from Starfinder.
My Hero Academy is superheroes, and this needs a special book, like the project d20 Spectaculars. I have said in the past WotC wishes to can publish its own version of d20 superheroes, to make money with the licence of those famous franchises.
Legend of Korra is practically XX century technology, and closer to wuxia subgenre. It would be easier to start from zero to can be adapted later.
A starter set of Legend of Zelda, Final Fantasy or Dragon Quest is possible, but it wouldn't be for D&D fandom but otaku collectors.
The mythology of Bleach and Tokyo Ghoul could be added to your D&D worlds, but they are more urban fantasy than gothic horror. Sometimes I wonder about the demiplane of dread (Ravenloft) to be too small to include all the monsters from famous horror franchises.
The shinigami from Death Note can be interesting monster for a couple of adventures, but not for long campaigns. Usually horror D&D is "the week monster".
* Yes, manga also can count, and even Korean webtoons.
