Suddenly finding himself in the Edo period, neurosurgeon Jin Minakata tries to return to the present day. But an oddly familiar stranger intervenes.

As Jin struggles to process the startling reality of his situation, a resurgence of a mysterious illness frightens residents across the city of Edo.

Just as Jin learns the shogunate will support his efforts to treat cholera patients with new techniques, he suddenly shows signs of infection.

Jin meets a courtesan with a striking resemblance to his fiancée in present-day Tokyo. She asks him to perform a life-saving operation on her father.

Jin takes on the ambitious task of producing penicillin to help Nokaze’s sister, a patient suffering terribly during the final stage of syphilis.

While visiting an eminent doctor of traditional medicine, Jin is pressed about his medical background — and soon gets an opportunity to prove himself.

When Jin learns of a patient with a terrible burn, he wants to help her. But the treatment requires a skin graft and a large amount of penicillin.

Nokaze asks Jin to treat a sick courtesan, but he needs stronger penicillin to cure her. Kyotaro gets an idea to secure the funds required to make it.

With both Nokaze and Saki developing strong romantic feelings for Jin, bells ring out across Edo warning of a dangerous fire engulfing the city.

When Jin visits Yoshiwara to examine Nokaze before her impending marriage, he notices something concerning during the exam but chooses to stay silent.

Jin wonders whether Ryoma might have traveled into the future during their tumble from the cliff. Saburi and Jin reexamine Nokaze’s symptoms together.