Pairs with Hat Handoff Promise. Ch. 1 is the handoff; Ch. 6 is the first time the world names him by the hat. From this page on, the audience and the in-world characters are co-trained to identify Luffy by the hat. When the hat’s deeper meaning is later revealed at Wano, the name itself becomes part of the foreshadowing — every time anyone has said “Straw Hat” across 1000+ chapters, they were unknowingly invoking Joy Boy’s artifact.
This is also the originating instance of Oda’s prop-as-introduction beat. Morgan (“Axe-Hand”), Shanks (“Red-Haired”), Whitebeard (“White-beard”), Blackbeard (“Black-beard”), Kuro of the Hundred Plans — the entire One Piece naming convention runs on the same principle: a character’s epithet is their primary visual prop. Ch. 6 page 14 is where this pattern is first executed on-page.
Technique stack
prop-tell — the hat is the most consistent visual prop in shonen history; the name is the prop made linguistic.
name-etymology — the moniker contains its own foreshadowing once you know what the hat is.