Farming Moon Crest in Sailor Piece — Drop Rates, Boss Summon, and Uses

The Moon Crest is one of the rarest materials in Sailor Piece, added as part of the Moon Update on March 31, 2026. You need it to unlock the Moon Slayer fighting style and, later, to craft that style's devastating F move. There is no shortcut — the only way to get it is by repeatedly defeating the Moon Slayer boss on Boss Island and hoping the RNG cooperates.

Quick answer: Defeat the Moon Slayer boss on Boss Island. The Moon Crest has a 0.30% chance to drop on Normal difficulty. Raise the boss difficulty and stack luck boosts to improve your odds.

Moon Crest Drop Rate and Source

The Moon Crest drops exclusively from the Moon Slayer boss. On Normal difficulty, the drop chance sits at 0.30%, making it the rarest item the boss can yield. For context, here is how it compares to the other Moon Slayer boss drops on Normal mode.

Increasing the boss difficulty raises every drop rate across the board, but it also demands more summoning materials and a much stronger build to survive the fight.

How to Summon the Moon Slayer Boss

The Moon Slayer does not roam the map. You have to summon it manually through the Boss Summoner NPC on Boss Island.

Step 1: Travel to Boss Island and locate the Boss Summoner NPC.

Step 2: Interact with the NPC, scroll down to the Moon Slayer boss entry, and submit the summoning cost: 1 Upper Seal, 700,000 Money, and 700 Gems. This spawns the boss at Normal difficulty.

Step 3: Defeat the boss. On Normal mode, it has roughly 1.25 billion HP, so you will need a high-damage build. After the kill, any drops — including the Moon Crest — appear automatically.

Step 4: Repeat. You can enable auto-spawn through the same NPC if you have enough summoning materials stockpiled, which saves time between runs.

Speeding Up the Moon Crest Grind

At 0.30%, you could statistically need over 300 kills before seeing a single Moon Crest on Normal. A few adjustments cut that number down significantly.

Raise the boss difficulty. Higher difficulty tiers improve drop rates for every item the Moon Slayer boss can yield, including the Moon Crest. The trade-off is a steeper summoning cost — more Upper Seals, more Money, and more Gems per attempt — plus a tougher fight.

Stack luck boosts. Equip titles, races, and clans that increase your luck stat. The Alter race, combined with the Celestial Favor title, is a strong pairing for luck. Allocate skill tree points into luck as well, and push your Ascension level higher for additional passive luck bonuses.

Optimize your kill speed. The faster each run takes, the more attempts you fit into a session. Use top-tier Devil Fruits, swords, and fighting styles to bring the boss down in as few hits as possible. A well-built character can shave minutes off every fight, which adds up over dozens of runs.

Where the Moon Crest Is Used

The Moon Crest serves exactly two purposes, both tied to the Moon Slayer fighting style. You will eventually need a total of three Moon Crests if you want the full style plus its F move.

Unlocking Moon Slayer Fighting Style

Visit the Moon Slayer seller NPC on the far end of Boss Island. Purchasing the style requires all of the following:

Crafting the Moon Slayer F Move

After unlocking the fighting style, head to the upside-down hand structure on the right side of Boss Island. The Moon Slayer F Move Mastery NPC sits near the King of Heroes seller NPC. The F move costs:

The Moon Crest grind is one of the steepest material farms in Sailor Piece right now, but the payoff — the Moon Slayer fighting style with its flashy AoE slashes and domain-style F move — is among the strongest late-game options available. Stack your luck, crank up the difficulty when your build can handle it, and keep summoning until the drop lands.