The ocean isn't a setting in this film, it's a character that knows more than you do. Masaaki Yuasa drowns you in animation and Daisuke Yoshida's soundtrack until the incomprehensible plot stops mattering, because you're not watching a story unfold, you're watching consciousness itself dissolve into something larger. Two boys who swim like they're remembering how to be water will stay with you long after you stop trying to understand what actually happened.
Ruka spends her summer at an aquarium where she encounters two mysterious boys, Umi and Sora, who move through water with an otherworldly grace that seems less like swimming and more like pure magic. Their origins remain shrouded in enigma, and their connection to the ocean runs deeper than anyone around them can fully comprehend. As Ruka becomes increasingly drawn into their world, strange phenomena begin unfolding across the planet. Fish vanish without explanation from waters everywhere, leaving scientists and authorities baffled by the coordinated disappearances. The boundary between the natural and supernatural grows thin as Ruka, the boys, and the adults watching over them find themselves caught in something far larger than a simple summer mystery. What begins as curiosity about two unusual kids transforms into a quest to understand a profound shift occurring within the world's oceans themselves. The film bathes everything in a dreamlike quality where wonder and unease coexist, where answers remain beautifully elusive, and where the sea holds secrets older than humanity itself.