Moon Slayer is a late-game melee fighting style in Sailor Piece introduced with the Moon Update on March 31, 2026. Inspired by Kokushibo from Demon Slayer, it puts a sword-like weapon in your hand but scales off melee stats rather than sword damage. The style is currently the highest-damage melee option in the game, with its locked F move capable of dealing upward of 15 billion damage on a fully optimized build.
Quick answer: Purchase Moon Slayer from the seller NPC on Boss Island after collecting the Six-Eyed Demon title, 37,500 Gems, 1 Moon Crest, 4 Crescent Shards, 9 Lunar Essence, 16 Demon Remnants, and 25 Upper Seals — all farmed primarily by repeatedly summoning and defeating the Moon Slayer boss.
Moon Slayer Fighting Style — Full Item Requirements
Seven distinct items must be turned in to the Moon Slayer seller NPC on Boss Island. Six of them drop exclusively from the Moon Slayer boss, while Upper Seals come from regular enemies throughout the game.
| Item | Quantity | How to Obtain | Normal-Mode Drop Rate |
|---|---|---|---|
| Six-Eyed Demon title | 1 | Moon Slayer boss drop (pity at 155 kills) | ~1% |
| Gems | 37,500 | Codes, chests, enemy drops | — |
| Moon Crest | 1 | Moon Slayer boss drop | 0.30% |
| Crescent Shard | 4 | Moon Slayer boss drop | 0.70% |
| Lunar Essence | 9 | Moon Slayer boss drop | 3.08% |
| Demon Remnant | 16 | Moon Slayer boss drop | 8.91% |
| Upper Seal | 25 | Any enemy in the game | Varies by NPC level |
The Six-Eyed Demon title is the single longest grind on this list. It carries an 85% damage buff — the highest title bonus currently in the game — and has a pity system that guarantees the drop after 155 boss kills. Upper Seals drop from enemies everywhere, but high-level NPCs on Lawless Island (particularly Arena Fighters) offer the best density and respawn speed for farming them.
Summoning the Moon Slayer Boss
The Moon Slayer boss does not auto-spawn. You need to visit Boss Island, interact with the Boss Summoner NPC, scroll to Moon Slayer in the list, and submit the following for each Normal-difficulty summon:
| Resource | Amount per Summon |
|---|---|
| Upper Seal | 1 |
| Money | 700,000 |
| Gems | 700 |
Higher difficulty settings raise the summoning cost but also increase every drop rate, making them more efficient once your build can handle the extra HP. The boss has 1.25 billion HP on Normal, so you need strong Devil Fruit powers, top-tier swords or fighting styles, a developed skill tree, and damage-boosting titles active before engaging.
An auto-spawn toggle exists in the summoning menu. If you have a large stockpile of Upper Seals and enough damage output to kill the boss quickly, you can leave the auto-spawn running to farm materials over extended sessions.
Moon Slayer Boss Drop Table (Normal Mode)
Beyond the materials needed for the fighting style itself, the Moon Slayer boss also drops the Moon Outfit accessory and other items worth collecting.
| Drop | Rarity | Normal-Mode Chance |
|---|---|---|
| Demon Remnant | Legendary | 13.41% |
| Lunar Essence | Legendary | 4.63% |
| Moon Outfit (Accessory) | Mythical | ~1.22% |
| Crescent Shard | Mythical | 1.06% |
| Six-Eyed Demon (Title) | — | ~1% |
| Moon Crest | Mythical | 0.45% |
The Moon Outfit is not just cosmetic. It provides 107% defense, 85% damage, and 15% damage reduction when equipped as an accessory, making it one of the strongest defensive pieces in the game. Its drop rate sits around 0.81–1.22% depending on difficulty, so expect many runs before it appears.
Moon Slayer Moveset Breakdown
Despite the sword-like visual, every move in the Moon Slayer kit is classified as a melee fighting style attack. The crescent-moon particle effects and purple crater impacts make it one of the flashiest styles in Sailor Piece, but the real draw is the damage output.
| Input | Description | Approx. Damage (Optimized Build) |
|---|---|---|
| M1 | Basic slashing combo with crescent moon particles on each hit | — |
| Z | Forward slash into a somersault strike; character moves during animation | ~2 billion |
| X | Two slashes followed by a continuous forward slashing sequence; stationary | ~2.2 billion |
| C | Lifts enemy with a swing, then fills the area with purple craters (large AoE) | 5+ billion |
| V | Cutscene move — massive ground-level cut that demolishes mobs in front of you | 10+ billion |
| F (locked) | Black domain with continuous slashes ending in a powerful forward burst | 15+ billion |
The C move is the primary mob-clearing tool thanks to its wide AoE. Z and X work better for single-target damage on bosses. V and F should be saved for burst windows during boss phases because of their long cooldowns.
Unlocking the F Move
The F move is not available when you first purchase Moon Slayer. A separate NPC handles its unlock — the Moon Slayer F Move Mastery NPC, located at the top of the hand structure on the right side of Boss Island, near the King of Heroes seller NPC.
Step 1: Equip the Moon Slayer fighting style. You must already own it before the NPC will interact with you.
Step 2: Roll the Upper Clan through clan rerolls. This is a mandatory requirement with no workaround. The Upper Clan is a legendary-tier clan that grants +40% damage, +50% max HP, +12% melee damage, and +12% luck.
Step 3: Collect the remaining materials from continued Moon Slayer boss farming and enemy drops:
| Item | Quantity |
|---|---|
| Moon Crest | 2 |
| Crescent Shard | 10 |
| Upper Seal | 85 |
Step 4: Interact with the Moon Slayer F Move Mastery NPC and submit all items. Once accepted, the F move unlocks permanently on your Moon Slayer style.
Farming Efficiency Tips
The total material cost across both the base unlock and the F move is steep: 3 Moon Crests, 14 Crescent Shards, 9 Lunar Essence, 16 Demon Remnants, 110 Upper Seals, and 37,500+ Gems. A few practical approaches can shorten the grind significantly.
Farm Upper Seals on Lawless Island before heading to Boss Island. Arena Fighters there have fast respawn timers and relatively high seal drop rates. Building a large reserve means you can summon the Moon Slayer boss repeatedly without interruption.
Increase your luck stat through ascension progress, skill tree nodes, luck-boosting runes like the Fortune Rune or Radiant Rune, and the Upper Clan itself once you roll it. Higher luck improves drop rates across the board.
Use private servers when farming the boss. Other players hitting the boss can dilute your damage contribution, and if you fall below the 10% HP threshold, you receive nothing for that kill.
Once your build can one- or two-shot the boss, enable auto-spawn through the Boss Summoner NPC menu. This lets you AFK-farm materials for extended periods without manual re-summoning.
Moon Slayer sits at the top of the fighting style hierarchy in Sailor Piece right now. The grind is long — expect well over a hundred boss kills to collect everything — but the Six-Eyed Demon title's 85% damage buff alone justifies the time investment, and the F move effectively turns most boss encounters into short work. If you are pushing endgame content, this is the style to prioritize.