Two years ago, Noda Tetsuya worked as a doctor. He was a medical intern trained by cardiac surgeon Terashima Koichi. One day, Koichi and his wife were murdered. At that time, Tetsuya lost his right hand. Koichi and his wife left behind their 8-year-old daughter Terashima Yui. Now, Noda teams up with Yui to lead an illegal secret surgery team, whose ultimate purpose is to find the truth behind the death of her parents. The team consists of 7 members. Noda is called Teacher and Yui is called Dr. Chocolate. She is only 10 years old, but she is a genius in the medical field. She was strongly influenced by her father and acquired advanced medical techniques through her interest in her father's work. To hire the black market surgery team, a fee of 100 million yen in cash is required as well as an NDA requirement and chocolate. The team are able to save the lives of patients no matter the circumstances, but a newspaper reporter begins to chase after them.