Unlike most filler movies, this story fits well into the timeline (post-Soul Society arc) and introduces lore about the Valley of Screams that was later referenced in the manga's final arc and the Can’t Fear Your Own World light novels, making it feel "pseudo-canon". Quick Guide to Other Bleach Movies
In this theater, the movies weren't fiction. They were —raw extractions of a soul's most intense regrets and joys. As the lights dimmed, the screen didn't show a film; it opened a Garganta-like rift. Suddenly, the audience wasn't just watching; they were standing in the middle of a snowy Karakura Town from fifty years ago.
The film reveals a dark secret regarding the Zanpakuto, Hyorinmaru . It explores the taboo of two different Soul Reapers manifesting the exact same spirit, introducing Hitsugaya's tragic former friend, Sojiro Kusaka.
Hitsugaya is accused of treason after a powerful artifact, the "King's Seal," is stolen during transport.
