Episode-4-The joueney Begins!/One piece At a Time

Meanwhile, Luffy and Zoro sail towards their next destination, but Luffy loses his signature straw hat when the boat jostles. Zoro recovers the hat, and its significance to Luffy is explained.

In his childhood, Luffy befriended Shanks, a pirate captain residing in his home village. While Luffy and the Red Hair Pirates were at a bar, Luffy unknowingly ate the Gomu Gomu no Mi, a Devil Fruit Shanks had acquired during his travels. Upon eating the fruit, Luffy's body immediately gained rubber-like properties, but he had permanently lost the ability to swim.

However, Luffy was terrorized and threatened by Higuma and his group of mountain bandits. Although Shanks and his pirates came to his aid, Higuma escaped, abducting Luffy. Higuma sailed out to sea on a small rowboat and threw Luffy into the sea for him to drown. However, a Sea King, a carnivorous sea monster, appeared and devoured Higuma whole, threatening to target Luffy next. Shanks rescued Luffy, but he lost his left arm in the process.

Eventually, the Red Hair Pirates departed from Foosha Village and set sail for the Grand Line. Just before he left, Shanks entrusted Luffy with his straw hat for him to protect. Throughout the years, Luffy cherished his hat to remind him of his idol.