One day after the an donut (fried donut filled with bean paste) which Jin had conceived as a confection to treat beriberi had created a sensation in Edo, he is asked by Matsumoto Ryojun of the Institute of Western Medicine and also the doctor to the shogun, to present the donut to Princess Kazunomiya, who is suspected to have beriberi. It is a big honour. But while Saki and the others at Jinyudo are overcome with joy, Jin broods alone as he has qualms that it could change history again …
Meanwhile, Jin is reunited with Nokaze, who was driven out of her tenement house and is seeking a job. Concerned for Nokaze, he encourages her to work at Jinyudo. Saki who has been managing the financially troubled Jinyudo also cheerfully welcomes Nokaze.
Jin later decides to present the donut. Accompanied by Saki, he visits Princess Kazunomiya, who has travelled incognito to watch Sawamura Tanosuke’s play. He presents it to her without incident, and is relieved to see her eat it as if it was delicious. However, that is short-lived as Princess Kazunomiya suddenly collapses on the spot …
“脚気（かっけ）に効く菓子”として、南方仁（大沢たかお）の考案した安道名津（あんドーナツ）が江戸で評判となる。仁は、奥医師でもある西洋医学所の松本良順（奥田達士）から、脚気の疑いがある皇女和宮（黒川智花）に、安道名津を献上してほしいと頼まれる。あまりの光栄な出来事に、橘咲（綾瀬はるか）をはじめとする「仁友堂」の面々が大喜びする中、再び歴史を変えてしまうことに躊躇（ちゅうちょ）が生まれ、仁はひとり思い悩む。
南方仁製作的甜點「安道名津」，因為對腳氣病很有效，在江戶頗受好評。某日，西洋醫學所的松本良順前來拜訪，表示皇女和宮可能罹患腳氣病，希望仁能夠獻上「安道名津」。
橘咲等「仁友堂」的成員，都感到十分光榮與欣喜。但仁卻因為自己可能改變歷史，而感到十分煩惱。
就在此時，仁遇見了正在找工作的野風。仁於是建議野風來「仁友堂」幫忙，而小咲也十分爽快的迎接野風...
