The Infinity Castle sequence in Demon Slayer film was built from millions of interconnected 3D architecture assets, arranged to feel as convincing as a real city and presented in a single continuous shot to give viewers the sensation of wandering through an endless, maze-like space.

Staff notes describe the challenge of linking countless pieces while keeping character movement readable, balancing complexity with clarity.

According to the film’s official booklet, the team spent about three years completing the Infinity Castle after Mugen Train, and the studio upgraded its pipeline and hardware so the work wouldn’t stretch to nearly ten years under older tech.

With the assets now established and the tools modernized, future scenes set inside the castle can be produced far more efficiently.

Absolute Cinema from Ufotable studio.