The Prison in the First Sea keeps a coat locked behind a gate at the top of its keep, and touching it starts a fight. The whole thing runs on one item you can walk past without noticing: the Cell Block Key, sitting out in the courtyard. Pick it up, climb the keep, and the office at the top opens.
Quick answer: Grab the Cell Block Key from the wooden platform in the prison courtyard, use it to unlock the Office Gate on the top floor of the keep, then interact with the cloak on the chair and defeat Megalo Guard [Lv. 250] to receive the Pink Coat and Black Cape.
Prison cloak secret requirements and rewards
The Prison sits west of Fountain City and normally serves players between Levels 190 and 250. The cloak itself has no level gate, but the boss it spawns is Level 250, so treat that as the real entry requirement. Everything happens inside the fortress, so you do not need to leave the island once you dock.
| Detail | Value |
|---|---|
| Location | Prison, First Sea (west of Fountain City) |
| Island level range | 190–250 |
| Required item | Cell Block Key |
| Locked object | Office Gate, top floor of the keep |
| Boss | Megalo Guard [Lv. 250] |
| Rewards | Pink Coat, Black Cape |

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“That coat belongs to the boss… don’t touch what’s his.”
Beating Megalo Guard (Lv. 250)
Megalo Guard is a proper boss, not a filler enemy, and the fight happens in the cramped office rather than out in the open. The room leaves little space to kite, so bring damage you can land at close range and be ready to reposition around the furniture. A well-levelled fruit with area attacks, such as Kitsune, clears the fight quickly.

Note: the guard makes it clear he is standing in for someone else, telling you “The Don isn’t here to deal with you himself. I’ll do him a favor taking care of you myself.” The coat’s owner never appears in the room.
How to confirm the cloak secret is complete
The moment Megalo Guard goes down, two on-screen messages appear: Took <Pink Coat> and Stored <Black Cape>. Both items land in your inventory, and the office no longer has anything to interact with. If you only see the dialogue and no reward text, the boss is still alive somewhere in the room.

Why the cloak secret does not trigger
There are only a few reasons this stalls, and all of them come down to order. The Office Gate will not open without the Cell Block Key in your inventory, so if you climbed straight to the top floor, go back down to the courtyard platforms and collect it. Reading the dialogue in the office also does not count as completing anything; the guard only spawns when you try to take the coat off the chair. And the rewards only drop on the boss’s death, so leaving the island or dying mid-fight means starting the encounter again.
Once you have both pieces, the office stays empty and there is nothing left to farm in that room. The rest of the island still runs as normal, with Warden, Chief Warden, and Swan on their usual spawns for anyone grinding levels or money in Blox Fruits.






