One day, Yongyongi, a dinosaur living on Dinosaur Mountain, comes down to the village where people live. Thump, thump, thump! The sound of his enormous footsteps echoes, and the people scatter in fear. But, a child named Haera approaches Yongyongi instead of running away. This is how their friendship begins.

However, while sitting atop a tree, Yongyongi suddenly starts to cry… What impact did the pure friendship between these two bring to the adults around them? This book invites readers to reflect on the richness of a world where many creatures live together and the purity that only children possess.