Due to human expansion causing damage to water sources, the ocean has ultimately suffered severe pollution. Unable to resist the erosion of marine pollution, the giant kelp Mokilign Motian from the ocean chooses to harness the dark elemental power of pollution to carry out a plan of revenge. A plant called "Chihua" begins to grow wildly in the human world and on Green Shadow Island, triggering an instant crisis. Elementary school students Luo Fei, Hao Lei, and Ling Tianheng from Riverside City return to Green Shadow Island and, together with Princess Lingxi of Green Shadow Island and their contracted Mokiligns, embark on a quest to find a legendary Sacred Heavenly Spirit Seed said to possess powerful purification abilities to counter the Chihua crisis. After overcoming numerous trials and successfully obtaining the Sacred Heavenly Spirit Seed, Luo Fei and his companions must not only confront the troubles created by Motian's faction but also face friction and misunderstandings among themselves. However, Luo Fei does not retreat. Leading his friends, he sets out on a journey to the Deep Sea Capital, ultimately defeating Motian, purifying Chihua, and eliminating the crisis.