Mikoto Saijou underwent a complicated heart surgery at birth and has been fascinated with pediatric surgery ever since. As a 10-year-old, he often visited the surgeon who operated on him, Dr. Mamoru Shindou. Shindou is quick to realize that Mikoto possesses amazing medical potential, particularly because of his spatial awareness and visualization. The two grow close, but Mikoto eventually moves to America, where he completes his education and residency.

Now, almost 10 years later, Mikoto returns to Japan and reunites with Dr. Shindou, eager to continue his journey to become the world's best pediatric surgeon.