During the course of his travels to find Blackbeard, Ace befriended the milk maiden Moda after she saved his life, and in return, he infiltrated the naval base G-2 to deliver a message to Vice AdmiralComil. During his undercover stint, he inadvertently helped reunite Moda with her parents, and acquired information on Blackbeard.
On an island somewhere in the Grand Line, Ace runs away from a restaurant after eating without paying. When he reaches the dock, he stops to ask people for information on Blackbeard. However, his searching only leads him to find a man known as Dr. Black Beard. Not realizing that he has the wrong person, Ace kicks Dr. Black Beard, which causes the angry villagers to throw him in the river.
After going downstream, Ace is rescued from the river by a girl named Moda. Moda takes the unconscious pirate to her house, where he wakes up. Ace and Moda officially meet, and Moda has a favor for him. In exchange for some of her milk, Ace agrees to deliver a letter.
Ace goes to the G-2 Marine base, where the letter is supposed to be delivered. After taking a Marine uniform from an unfortunate man, Ace infiltrates the base, his first order of business being to help himself to food. However, he overhears a Marine badmouthing Whitebeard and punches him, which causes the Marines to chase after him.
However, in a different part of the Marine base, a meeting is quickly turning sour because the coffee is extremely bitter, and even the commanding officer, Comil, hates it. Elsewhere, a marine scout ship approaches the base, but it gets set on fire by some pirates. The Marines are very worried because top-secret documents are on the scout ship, when one of them jumps into the conflagration. The Marine turns out to be Ace, who carries some documents out while still on fire. However, the Marines quickly deduce Ace's identity and chase him down again. However, before escaping, Ace hands Moda's letter to Comil, the intended recipient. Comil reads Moda's letter, which asks the Marines if they would like to buy her milk.
A Marine food ship stops by Moda's home to purchase her milk. It is revealed that the cooks on the ship are Moda's parents, and they happily embrace Moda. Due to now having her milk, the Marines' coffee tastes much better. Meanwhile, Ace sails off, having gotten information on Blackbeard from the Marine scout ship, and is now ready to take on the pirate.