A kid finds a dinosaur and keeps it, and the movie understands that this is enough. There's no villain monologuing about exploitation or scientists chasing it with nets, just a boy learning what it means to love something that doesn't belong to your world. Coo dies at the end, and the movie doesn't apologize for it.
A freak storm deposits something impossible on a remote island: a living, breathing dinosaur no bigger than a child. Yusuke, a restless teenager, discovers the creature washed ashore and smuggles it home, where his father agrees to keep it hidden. They name it Coo, and what begins as a secret quickly becomes something neither of them anticipated: a genuine bond between boy and ancient animal. But Coo's existence attracts dangerous attention. Scientists, collectors, and shadowy organizations converge on the island, each convinced that a 65-million-year-old creature represents fortune, knowledge, or power. Yusuke finds himself caught between protecting his new friend and a world determined to exploit it. As Coo grows and its origins deepen into mystery, the real question emerges: where does this creature truly belong, and what will Yusuke sacrifice to keep it safe? The film balances quiet moments of wonder and companionship against mounting tension, creating a story about innocence colliding with human ambition.