En route to Arabasta, Nami falls ill. Without a doctor aboard the Going Merry, the Straw Hats must decide whether to stay the course or find more immediate help.
If the Straw Hats have any chance of saving Nami, they must carry her up a mountain to see the sole doctor of a nameless, winter island. While Sanji and Luffy fight off the wilderness, a despicable king makes an unwanted return.
A devastating avalanche sweeps Drum Island and puts everyone at risk, but Luffy-step-by-step, hand-over-hand-continues his death-defying ascent up the mountain. Meanwhile, Vivi, Usopp, and Zoro reunite in the wake of the disaster.
Enter Chopper: a talking, transforming blue-nosed reindeer who was trained by Dr. Kureha in medicine. The Straw Hats immediately see the positives and want him on their crew, but Chopper must first deal with the great pain in his heart.
Chopper began life as an ordinary reindeer but was shunned by his own kind because of his blue nose. Even after eating the Human-Human Devil Fruit, humans wanted nothing to do with him. That is, until Chopper met a certain quack doctor.
Wapol and his comrades reach the mountaintop castle to wrest control of it back from Dr. Kureha and Chopper. Luffy, Sanji, and Chopper go head-to-head against his powers, vowing to keep Wapol and his men from bringing down Hiriluk's flag.
Chopper counters the combined Chessmarimo with an item that expands his Zoan fruit abilities. Wapol slips away into his old castle, but Luffy runs after him to force a final showdown.
Finally convinced to join the Straw Hat Pirates, Chopper announces his intentions to Dr. Kureha. While she doesn't receive the news well at first, she decides to give the Straw Hats a fond parting gift while they exit the island.
