Traumatized but brilliant brain surgeon Minakata Jin has waited years for the woman he loves to awake from a coma after the life saving surgery he performed to remove her supposedly inoperable brain tumor. One evening while a mysterious man is brought in with a head wound. Jin reluctantly performs the surgery that saves his life and muses on the strange nature of what is discovered in the operating room. When the patient revives and tries to sneak out of the hospital the good doctor chases him and suddenly finds himself transported back in time....

Jin learns that the mysteriously familar man is Sakamoto Ryoma, called the hero of the final days of the Tokugawa Shogunate, and wonders if Ryoma had been his unidentified patient at the hospital some 140 years into the future? Fearful of altering history he resists the efforts of Ogata Koan, head of the Western Medicine Institute' s entreaties for aid in treating the outbreak of cholera striking the city even as those he's come to care for begin to fall ill...

Jin has taught Ogata, Saburi and the other doctors of the Western Medicine Institute what he can of how to fight this latest outbreak of disease, when he himself falls ill. Who will treat the doctor when he becomes the patient? A terrible tragedy strikes and Jin ponders the mutability of time and whether his actions can truly change anything...