Childhood friends Chrono and Lucca join the townspeople of Truce gathered in Leene Square for the Millennial Fair, a festival held once every thousand years to commemorate the founding of the Kingdom of Guardia. While the katana-wielding Chrono simply wants to enjoy the festivities, Lucca decides to take the opportunity to show off her latest invention. Remembering that Lucca tried to hide it from him the day before, Chrono begins searching for her device. Along the way, he encounters Marl—an iron-willed girl armed with a crossbow—an encounter that may mark the beginning of an adventure across time itself.