Grand Line Map

Structural lore — a single-copy item established as a chapter-defining MacGuffin in Ch. 8.

What we know

Ch. 8 page 14-15: a rolled parchment map of the Grand Line exists as a single, hand-clutched artifact.
Ch. 8 page 15: held by Buggy aboard his flagship in Orange Town until Nami steals it directly from him.
Ch. 8 page 15: Buggy mooks describe its loss as a fatal crisis (“If we don’t get that map back, we’re dead!”) — implying Buggy’s wrath over the map is itself a known fact within his crew.
Ch. 8 page 15: Nami clutches the parchment and exults “I finally have it! A map of the GRAND LINE!!” — establishes the map as a prized and sought artifact, not a casual prop.
The Straw Hats’ entry to the Grand Line is positioned (by this chapter’s framing) as gated on possession of this map.

Pre-Ch 8: Buggy holds the map; how he acquired it is not on-page in Ch 8.
Ch 8 page 15: Nami steals the map directly from Buggy.
Ch 8 page 19: Nami still has the map; offers Luffy a team-up.
Status as of Ch 8: in Nami’s possession.
Ch 101 page 4 — first operational test. Nami’s chart-reading directly references the map’s labels (Reverse Mountain, Canal, Red Line / REDLI, Roguetown ×, GRANDLINE, You Are Here arrow). The map’s accuracy is confirmed by the rest of the chapter — Reverse Mountain is real, the canal is real, the lighthouse is real. Usopp’s ‘BUT YOU STOLE THAT MAP FROM BUGGY. CAN WE TRUST IT?’ triggers the first explicit in-narrative discussion of map-provenance; Sanji defends via ‘NAMI’S ALWAYS RIGHT WHEN IT COMES TO CHARTS AND NAVIGATION’ — the navigator-authority-over-map-source doctrine is canonized. The map’s secondary insufficiency (the Log Pose requirement for post-Reverse-Mountain navigation) remains pending — Ch. 105.

What is the One Piece — what reaching the Grand Line costs and reveals.
Open: will this specific map actually get the Straw Hats into the Grand Line? The chapter framing implies yes; the eventual answer (Reverse Mountain entry needs more than a map — it needs a Log Pose) reframes the Ch 8 map as a misleadingly partial solution. Tracked in Grand Line Map MacGuffin.