One Pace — Whole Cake Island 9

One Pace Whole Cake Island episode 9 ("The Iron Mask") covers manga chapters 839–840.

The Iron Mask

One Pace

Whole Cake Island 9The Iron Mask

Manga chapters

Chapter 839
Chapter 840

Source anime episodes

Episode 800
Episode 801
Episode 802
Episode 803

What One Pace is

One Pace is a fan project that re-edits the Toei anime to match the manga's pacing. It cuts filler, recaps, and stretched scenes, so a single One Pace episode usually covers the same ground as several broadcast episodes — here, chapters 839–840 re-cut from anime episodes 800–803.