Lily visits a frog-themed amusement park with her parents. She draws a sword from the Frog Castle, an act linked to a local legend where defeating a large snake grants a wish from the Frog King. After defeating the snake, Lily is transported to Frog Land. The Frog King issues her a challenge: open the Gate of Hope before a child hatches from a roe placed before her, or be turned into a frog. Immediately, a man named Knodo appears, claiming to be her future little brother. Confused and uneasy at this sudden declaration of kinship, Lily attempts to flee from Knodo. He pursues her, and their chase ends with both falling headfirst into water.