The Atomic Sword is one of the strongest endgame weapons in Sailor Piece, and getting it is a serious commitment. Introduced in Update 7.0 (also called the massive March 2026 update), this sword is inspired by Cid Kagenou from The Eminence in the Shadow anime. Its AoE kit hits hard across every difficulty tier, and the fully unlocked F move deals 1.7 billion damage. The grind is real, but the payoff is worth it.
Where do you find the Atomic Sword NPC?
The sword is sold by an unnamed NPC on Lawless Island, one of the later locations in the Portal list. According to the IGN wiki guide, when you arrive on the island, follow the path from the portal toward the corner of the island. You will pass the Atomic Master NPC, but that is not who you need. Keep going along the outer edge until you find a second NPC that looks similar but has no name floating above them. That is the seller.
This NPC will show you the full list of requirements before you can make the exchange. None of it is cheap.
Atomic NPC on Lawless Island
What do you need to unlock the Atomic Sword?
Here is the complete list of requirements:
- Eminence Incarnate Title (equipped)
- Shadow Sword (in inventory)
- 45,000 Gems
- 1x Atomic Omen
- 3x Eminence Essence
- 9x Shadow Remnant
- 16x Magic Shard
- 80x Abyss Sigil
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Before starting this grind, reroll your character's Species to Kitsune for a +25% Luck boost. You can also stack Luck through Runes, Clan levels, Boss Kill Titles, or the in-game Shop. Higher Luck directly improves drop rates on every item in this list.The Abyss Sigils are the only material that does not drop from the Atomic boss. Everything else, including the Eminence Incarnate Title, Atomic Omen, Eminence Essence, Shadow Remnant, and Magic Shard, comes from farming that single fight.
How to farm the Atomic boss efficiently
To spawn the Atomic (Cid) boss, speak to the Atomic Boss Summoner at the center of Lawless Island. You pick the difficulty before spawning, and the Sigil cost scales with it.
On Normal difficulty, the Atomic boss has 2,000,000,000 health. Higher difficulties cost more Sigils but push up the drop rates on rarer items. For the Eminence Incarnate Title specifically, Extreme difficulty nearly doubles the chance compared to Normal.
Here are all the Atomic boss drops on Normal difficulty, per Sportskeeda:
- Magic Shard: 13.75%
- Shadow Remnant: 4.50%
- Atomic Outfit: 1.19%
- Eminence Essence: 1.11%
- Eminence Incarnate Title: 0.7%
- Atomic Omen: 0.4%
warning
The Atomic Omen has the lowest drop rate at 0.4% on Normal. If you are running low on Sigils, consider bumping to Hard or Extreme to squeeze more value out of each spawn.
A useful trick noted by Sportskeeda: position yourself near the Arena Fighter mobs while fighting the boss. That way you can farm Abyss Sigils from the mobs and battle the boss simultaneously, keeping your Sigil supply topped up.
Atomic boss difficulty selection
How do you get Abyss Sigils?
Abyss Sigils drop from two enemy types: the Ninja enemies on Ninja Island and the Arena Fighter enemies on Lawless Island. The drop rate is low, so stacking Luck through Titles, Spec Passives, and other mechanics is the most direct way to speed this up. According to Sportskeeda, interacting with Quest NPCs before fighting these enemies also earns Money and EXP as bonus rewards, so do not skip that step.
You need 80 Sigils for the sword purchase itself, plus additional Sigils for every boss spawn during your farming sessions. Budget accordingly.
How to get the Shadow Sword
The Shadow Sword (also called Cid V1) is a prerequisite for the Atomic Sword, and it has its own separate grind. Head to Dungeon Island and find the Shadow NPC on top of the building. According to both IGN and Beebom, the Shadow Sword requires:
- Shadowborn Race
- 10,000,000 Money
- 15,000 Gems
- 1x Atomic Core
- 4x Shadow Essence
- 8x Void Seeds
- 20x Umbral Capsules
The Shadowborn Race is available to all players but requires a Race Reroll, which is RNG-based. The remaining materials come from the Shadow Dungeon, accessed through the Dungeon Master NPC. Epic and Legendary Chests from strong enemies on Lawless and Ninja Island also have a high chance of dropping useful rewards during this phase.
danger
Do not skip the Shadow Sword grind hoping to buy your way around it. The Atomic NPC checks for the Shadow Sword in your inventory before the exchange. There is no shortcut here unless you buy the full bundle from the Shop.
How to unlock the Atomic Sword F move
After getting the sword, head to the left end corner of Lawless Island and talk to the Atomic Master NPC to start the Mastery questline. Beebom's guide documents three quests you need to complete:
- Kill the Atomic boss 20 times on Hard or Extreme difficulty (requires at least 60 Abyss Sigils for Hard)
- Obtain the Eminence Clan (get Clan Rerolls from enemy drops, boss kills, or Sailor Piece codes)
- Reach Floor 51 in the Infinite Tower 5 times (access via Tower Island's Infinite Tower Portal)
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Stack the Clan Reroll grind with your regular boss farming sessions. Enemies and bosses both drop Clan Rerolls, so you will naturally accumulate them while working toward the 20 Atomic boss kills.
Can you skip the grind and buy it directly?
Yes. The in-game Shop sells a bundle containing only the Atomic Sword for 1,449 Robux, as confirmed by both Sportskeeda and Beebom. Larger bundles also include weapons like the Abyssal Empress Sword. Buying from the Shop bypasses the material requirements entirely, but you still need to complete the Mastery questline to unlock the F move.
For everything else in Sailor Piece, browse more guides on GAMES.GG to keep your progression moving. The full breakdown of requirements and drop rates is also covered in detail on Beebom's Atomic Sword guide and the IGN Sailor Piece wiki.