The Demon King, sealed by Shennong in the Hundred Herbs Wonderland for thousands of years, awakens due to the increase in unhealthy lifestyles among modern humans. To seal the Demon King once more, Li Shizhen, the Medicine God responsible for guarding the Hundred Herbs Wonderland, dispatches Herb Boy and Yan Sheng—a 12-year-old human boy who is the true master of the Medicine Scripture Stone—to the Hundred Herbs Wonderland to gather the essence of a hundred herbs and re-seal the Demon King. The Demon King, on one hand, absorbs energy from the unhealthy habits of children in the human world to restore his power; on the other hand, he orders his four subordinates to stop Yan Sheng and the others from collecting the herbal essences. Faced with this immense challenge, Yan Sheng and Herb Boy dutifully accept Li Shizhen's proposal, using the "Compendium of Materia Medica" and the Medicine Scripture Stone to collect the herbal essences hidden within the Hundred Herbs Wonderland, aiming to seal the Demon King before the arrival of the Medicine and Food Festival on June 13th. In the end, through everyone's efforts, they successfully gather the essences of a hundred herbs, defeat the Demon King, and help people realize the importance of a healthy lifestyle. From then on, Yan Sheng and Herb Boy become ambassadors of health in people's daily lives.