Debut filmmaker Yûki Igarashi had a golden opportunity with this project: delivering the first major cinematic adaptation in decades of Princess Knight, the groundbreaking postwar manga by Astro Boy creator Osamu Tezuka. Unfortunately, this exceptionally loose adaptation falls flat. It plays it safe by focusing exclusively on the conventionally feminine traits of protagonist Sapphire (voiced by Saya)—stripping away the gender-fluidity that made the original source material truly pioneering—and stumbles into blandness with generic character arcs and formulaic battle-anime tropes.
Sporting a hair bow large enough to rival Minnie Mouse, Sapphire is a royal heir forced into exile after a “Nergal”—a monstrous, flying earwig-like creature—destroys her home realm of Silverland. While wandering alongside her lady-in-waiting, Zirco (voiced by Mayumi Shintani), she seeks shelter in neighboring Goldland. Desperate for money, she takes a job in the local mines, which extract the crystals used to appease the rampaging Nergals. When another attack strikes, she plunges into a mystical crystal pool. The liquid awakens her head ribbon, transforming her into the formidable Princess Knight, a warrior strong enough to beat back the interdimensional beasts. This display catches the eye of local nobleman Velvet (Seiran Kobayashi), who is desperately looking for a way to break the Nergal occupation.
While it is understandable that Igarashi wanted to honor the innocent charm of Tezuka’s classic era, surely that could have been achieved while forging new paths for the Princess Knight franchise? Instead, the film delivers a sugary, moralizing protagonist who endless preaches about altruism—a tiresome trait that quickly spreads to her thoroughly forgettable companions. Furthermore, the mandatory aerial combat sequences fail to inject the kind of manic, imaginative energy and diverse special abilities seen in modern hits like One Piece or My Hero Academia.
That said, the animation itself is undeniably gorgeous. It blends a stunning variety of visual styles, juxtaposing elegant European pageantry with striking 2D backgrounds, punctuated by chibi-style comedic freakouts and charming shadow-play interludes amid the chaos. This artistic flair highlights a creative daring that is sadly missing from the narrative; by failing to lean into Tezuka’s wilder, more avant-garde sensibilities, the adaptation ultimately amounts to little more than standard, run-of-the-mill empowerment fluff.