In 2049, to complete the "Chinese Inventions Database" and trace the origin of Chinese inventions, Science Museum staff Lu Ren is chosen by AI administrator Lingsu to launch a cross-spacetime journey (Tian Gong Mission). He successively travels through the Eastern Han Dynasty, the Northern Song Dynasty, and the Ming Dynasty, helping Cai Lun improve papermaking, Bi Sheng create movable type printing, and Li Shizhen publish "Compendium of Materia Medica", personally experiencing the explorations and breakthroughs of the sages. In every lifetime, Lingsu incarnates as a companion of different eras; through three lifetimes of training, the perroutine and slack Lu Ren gradually becomes a civilization guardian with awe in his heart, and Lingsu also learns what "human hearts" mean along the companionship. A guardianship spanning a millennium reflects the spirit of exploration engraved in the bones of the Chinese people.