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Repair Windows errors before they cause bigger problemsFix Now →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →To get Rengoku in Blox Fruits, obtain a Hidden Key at Ice Castle in the Second Sea, then use it to open the black chest in the hidden passage beneath the Awakened Ice Admiral’s staircase. You can get the key from the Awakened Ice Admiral, Arctic Warriors, or Snow Lurkers; the reported drop chances are unofficial wiki estimates.
Where to get Rengoku
Rengoku is a Legendary sword obtained from a chest at Ice Castle. The castle is in the Second Sea. The fan-maintained Ice Castle guide lists the island’s level range as 1350–1425, with Arctic Warrior quests starting at level 1350, Snow Lurker quests at 1375, and the Awakened Ice Admiral quest at 1400.
How to get Rengoku
- Travel to Ice Castle in the Second Sea.
- Defeat enemies until a Hidden Key drops. The Awakened Ice Admiral is the boss source; Arctic Warriors and Snow Lurkers are the regular-enemy sources.
- Go beneath the side of the staircase where the Awakened Ice Admiral spawns. Pass through the wall to enter the hidden passage and find the black chest with a keyhole.
- Use the Hidden Key on the chest. Opening it rewards Rengoku, according to the Ice Castle guide.
Which enemies should you farm for the Hidden Key?
The fan wiki reports a 5% Hidden Key drop chance from the Awakened Ice Admiral and a 0.5–1% chance from Arctic Warriors or Snow Lurkers. These figures come from the unofficial Hidden Key guide, updated September 24, 2026, and are not rates confirmed by the game’s publisher.
| Source | Reported Hidden Key chance | What to consider |
|---|---|---|
| Awakened Ice Admiral | 5% (unofficial wiki figure) | Higher reported chance; farm the boss if you are ready to fight it. |
| Arctic Warriors or Snow Lurkers | 0.5–1% (unofficial wiki figure) | Lower reported chance; an alternative if you prefer fighting regular enemies. |
The figures do not establish how many defeats you will need or how long the grind will take. The sources also do not provide a reliable time comparison between boss and regular-enemy farming, so choose based on which fights suit you.
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Hidden Key details that can prevent a wasted trip
- You can enter the passage without a key. You still need the Hidden Key to open the chest, unless you already own Rengoku, according to the Hidden Key guide.
- Use the right key. The Rengoku chest takes a Hidden Key. A Library Key is associated with Phoeyu and Death Step, not this chest.
- Open the chest before leaving the session. The wiki says Hidden Keys and Library Keys obtained from NPCs do not persist in your inventory after leaving the game. This is unofficial guidance and may change.
- Treat drop rates as estimates. The wiki pages are fan-maintained, identify themselves as unofficial, and do not establish publisher-confirmed odds or a guaranteed number of kills.
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