Kimetsu no Yaiba Infinity Castle,' the first in a trilogy, is set in the same world as 2020 hit 'Mugen Train,' the most successful anime film of all time.

At its end, however, the group were ambushed and drawn into the titular Infinity Castle, the HQ for villain Muzan Kibutsuji and his motley crew of fearsome 'Upper Rank' demons. Infinity Castle will be the first of a trilogy of movies, with each adapting the manga arc of the same name and bringing the story to a close.