The seven map pieces in Sailor Piece are the second gate on the way to Sea 2, sitting right after the two Ancient Fragments. Each piece drops from a specific group of open-world bosses, and the drops are random, so the real work is knowing exactly which bosses to farm instead of cycling through every spawn on the map.
Requirements before map pieces can drop
Map pieces only begin dropping once the Sea 2 questline is active, which means you need the two Ancient Fragments collected first. Without that prerequisite, bosses will not roll the map piece drop at all, even if you are hitting the correct targets.
Three boss types are excluded from the drop pool entirely: Boss Rush, Infinite Tower, and Dungeon bosses. Only open-world boss kills count, whether they spawn naturally or are summoned with a key.
All 7 map pieces and the bosses that drop them
Each map piece has more than one possible source in most cases, which matters because drops are not guaranteed per kill. If one boss has a long respawn or a contested spawn point, switching to the alternate target for the same piece is usually faster than waiting.
| Map Piece | Bosses and locations |
|---|---|
| Piece 1 | Knight / Excalibur (Boss Island) or Cursed Vessel (Shibuya Station) |
| Piece 2 | Limitless Sorcerer (Shibuya Station) or Cursed King (Shibuya Station) |
| Piece 3 | Qin Shi (Boss Island) or Solo Hunter (Sailor Island) |
| Piece 4 | Vampire King (Sailor Island) or Anos (Academy Island) |
| Piece 5 | Manipulator (Hollow Island) or Slime / Demon Lord (Slime Island) |
| Piece 6 | Soul Reaper (Boss Island), Blessed Maiden (Boss Island), or Strongest of Today (Shinjuku Island) |
| Piece 7 | King of Heroes (Boss Island) or Strongest of History (Shinjuku Island) |
A few of these bosses go by renamed versions of familiar anime-inspired characters. Solo Hunter is the Jin Woo boss, Manipulator is the Aizen boss, Soul Reaper is the Ichigo boss, and King of Heroes is the Gilgamesh boss. The in-game names are what you will see on the boss summoner and nameplates.
Where to summon each boss
Most of the Boss Island targets require a boss key from the summoner on that island. Shinjuku Island bosses need element-specific keys, usually tied to the boss theme (a limitless key for Strongest of Today, a malevolent key for Strongest of History). Slime Island uses a slime key for its boss spawn, and Academy Island handles Anos through its own spawn rotation.
Vampire King is the one that tends to stall runs. It spawns on Sailor Island on a roughly five-minute cycle, but it shares the location with Solo Hunter, so you can end up waiting through the wrong spawn when you are specifically chasing piece 4.
How the drop system actually works
Map pieces are rare random drops, estimated at under a 5% chance per qualifying kill. Every boss you defeat rolls independently, so streaks of zero pieces across ten or more kills are normal and not a bug.
When a map piece drops, you get an on-screen notification identifying which numbered piece you received. Track what you already own, because getting a duplicate on a boss that could have dropped a piece you still need is a common source of wasted runs. If you already have piece 3, for example, there is no reason to keep farming Qin Shi.
Efficient farming order
The fastest path is to clear pieces with the most flexible sources first, then push the bottlenecks last. Piece 6 has three possible bosses, so it usually resolves quickly during general farming. Pieces 2 and 7 have two bosses on nearby islands (Shibuya Station and Shinjuku Island / Boss Island), making them easy to alternate.
Save dedicated attention for piece 4. Vampire King's respawn timing and shared spawn with Solo Hunter means it is the piece most players finish on. If the Vampire King roll keeps failing, rotate to Anos on Academy Island instead of idling for the next Sailor Island respawn.
A strong damage build matters more than it looks for this quest. Faster clears mean more drop rolls per hour, and several of these bosses scale high enough that an undertuned character can lose an entire spawn window to a single kill.
Knowing when you are done
Once all seven pieces are in your inventory, the Sea 2 quest advances on its own. You will see the map-pieces objective marked complete and the next step in the Sea 2 chain unlocks, which is when you can actually sail to the second sea. If the quest has not updated after a drop, open your inventory and confirm the numbered pieces you own are 1 through 7 with no gaps; a duplicate notification can easily look like a new piece during a fast farm.