Within the Inner Chambers—the luxurious garden of women destined only for the ruler of the nation—work burdens everyone from the lowest maid to the highest-ranking concubine. After arriving on the same day to start as servants, Asa and Kame quickly become friends. The two vow to overcome any challenges in their way as they begin their splendid new lives. In the midst of intricate power relations, uncanny rituals, and untold secrets, the Inner Chambers are thrown into an uproar when strange incidents disrupt the arrangements for an upcoming ceremony. While shogunate officers are dispatched to investigate the matter, the strange Medicine Seller knocks on the gates and demands access to these forbidden quarters, claiming that their situation is much more dangerous than they imagined.

The release of Mononoke Movie 1: Karakasa was delayed from 2023 to the summer of 2024. The movie won the Bronze Award in the Best Animated Feature category at the 28th Fantasia International Film Festival in 2024. The film was released on Blu-ray and DVD on December 18, 2024.