Two years ago, a genius surgeon called "Dr. Chocolate" appeared in Singapore. They have three conditions: 100 million yen in cash, a signed NDA, and a suitable amount of chocolate. Under "Teacher," the "Chocolate Company" forms in Japan.
Teacher and Dr. Chocolate are working to unravel a mystery from two years ago. Yui hasn't been to school since then, but wants to go after making friends. When a former patient dies mysteriously, Teacher and Okuzumi track down the killer.
Yui has started attending school happily, but can't play after school because she has surgeries. When an idol loses consciousness in a TV station bathroom, Dr. Chocolate has to perform an operation without any proper equipment.
Teacher is called into Yui's school when she is accused of being violent towards an older student. Unagi defends Yui for doing the right thing. The Chocolate Company receives a request to cover up medical malpractice, but Unagi refuses.
Teacher invites Okuzumi to dinner as a thank you, not knowing that she has discovered the true identity of Dr. Chocolate. Zandaka fights a gambling addiction and thinks of his daughter. A new client appears with a mysterious tattoo.
Two actors are in a motorcycle accident, but going to the hospital would reveal their relationship. Three days prior, Okuzumi writes an article unmasking Dr. Chocolate's identity, but Teacher calls it half-baked and invites her somewhere.
Teacher and Okuzumi meet with Detective Yoda, who seems to know something about the incident from two years ago. Yui learns that the Kitazawas offered to take care of her, but Teacher declined. Gilbert leaks information about the Company.
A member of the Megumi group who may have information on the incident from two years ago is seriously injured in an explosion. Okuzumi comes to the Company's hideout and asks Yui about something Teacher said.
The Chocolate Company abandons their hideout after an article exposing Dr. Chocolate is published. Ashiyu begs Yui to help a patient, but it turns out the patient isn't her friend, but a stranger. Teacher has a confrontation with someone.
Teacher and Okuzumi rush to rescue Yui, but the place where she should be is empty. Two members of the Megumi group are arrested. The mastermind is discovered and reveals the story of the incident two years ago. Yui's life is in peril.
