A fourth-grade student in Tokyo discovers a baby kappa, a mythical water creature, and names it Coo. The two become friends, but Coo struggles to adjust to modern life and longs for his own family. They embark on a road trip to find Coo's kind on a hot summer day.

Summer Days with Coo
A young boy discovers a mystical water spirit, a Kappa, and befriends it as it learns to adapt to the challenges of modern society.