He's in Marvel, working behind the scenes.

Gu Qing transmigrated to the Marvel universe and activated the Dimensional Doll System, which allowed him to obtain powerful dolls from other worlds.
At the start, summon Kibutsuji Muzan and the Twelve Demon Moons.
But this is only the beginning.
Witch Cult, Vongola Family, Espada, Great Tomb of Nazarick, Akatsuki, Godzilla, Land of Light...
It's unclear when exactly, but one after another, behind-the-scenes forces have emerged in the Marvel universe.
The world is dominated by movies, with comics playing a secondary role.