Rengoku is one of the coolest and strongest swords in Blox Fruits. It’s a fiery Legendary sword perfect for fighting in the Second Sea. This guide explains everything super simply, step by step, like talking to a friend.
You need level 700 or higher to enter the Second Sea and reach Ice Castle.
What You Need Before Starting
Your character must be level 700 or higher to unlock the Second Sea. If you’re still in the First Sea, find a boat dealer near the docks and pay to travel across. Strong weapons, fruits, or fighting styles make the grind easier, but even basic gear works if you’re patient.
Super Easy Steps to Get Rengoku (Full Details)
Follow these exactly. No rush! Each step builds on the last.
Find Ice Castle: Head to the Second Sea and sail or fly toward Frozen Village. It’s a snowy area with ice everywhere. Right beside it stands Ice Castle – a massive icy fortress with tall white towers, frozen walls, and slippery floors.
Hunt for the Hidden Key: This is the trickiest part because the drop rate is super low. Around Ice Castle, defeat Arctic Warriors or Snow Lurkers (both level 1350). These ice soldiers patrol outside and drop the Hidden Key with less than 1% chance – expect 30 minutes to several hours of farming. For better odds, go inside and wait for the Awakened Ice Admiral boss (level 1400). He spawns every 20-30 minutes with about 5% key drop. Pro Tip: Spend 250 Robux on the “2x Boss Drops” Game Pass from the in-game shop to double your chances. Always activate Instinct to see attacks and dodge his ice blasts!
Enter the Secret Room: Step inside Ice Castle’s main entrance. Head right to the wide stairs near where Awakened Ice Admiral appears. Under those stairs, spot a fake wall just left of the red carpet – it looks solid but isn’t! Walk straight into it. You’ll phase through to a small hidden room glowing with a golden chest.
Open the Chest: Make sure your Hidden Key is in your inventory (bottom screen). Click the shiny chest. Instantly, you receive the Rengoku sword and unlock the “Samurai” title that appears above your character!
Done! Open your inventory, drag Rengoku to your sword slot, and equip it. The blade glows bright red with roaring flames – perfect for showing off.
Rengoku’s Cool Attacks (Moveset)
| Attack/Key/Mastery Needed | What It Does (Super Simple)/Wait Time |
|---|---|
| Demon Slayer (Z key), Mastery 150 | Dash forward super fast while slashing 3 times through flames. The final hit breaks enemy Instinct (stops their dodge), plus burns for 2 seconds of extra damage. Ideal to start combos and catch runners! 9 second cooldown. |
| Burning Slash (X key), Mastery 350 | Tap quickly for a forward fire wave that burns the ground ahead. Hold the key for a massive area explosion of flames everywhere! Both versions break Instinct. Perfect for clearing groups or PvP pressure. 13 second cooldown. |
Pro Tip: Hit weak sea beasts or NPCs repeatedly to build Mastery fast. Max both moves for full power.
Make Rengoku Even Stronger (Upgrade It)
Visit any Blacksmith – look for the hammer icon guy in First Sea towns like Starter Island or Second Sea Cafe. Hand over these exact materials for a permanent +8% damage boost:
- 8 Vampire Fangs: Farm nighttime Vampires wandering Third Sea Graveyard island.
- 20 Magma Ore: Drop from Military Soldiers or the Magma Admiral boss in fiery First/Second Sea zones.
- 15 Scrap Metal: Easiest farm – Pirates and Brutes drop it across all seas.
The upgrade makes every swing hit harder forever. Totally worth the extra grinding!
Quick Tips to Make It Easier
- Fast Key Farm: Equip Flame fruit (fire melts ice enemies fast) or play with friends to share kills.
- Avoid Mistakes: Never drop your key by dying carelessly. Swords weaken in water, so stick to land fights. Grind safely with Observation Haki.
- Why It’s Awesome: Crushes Blade race players, huge knockback, fire effects look epic in PvP duels. Downsides: Long key hunt, loses power vs water users, Mastery takes time to unlock.
- Level up quickly by redeeming active Blox Fruits codes for 2x XP boosts.
Extra Info (No Changes in 2026)
Rengoku joined in Update 13 with moves reworked in Update 20 (added Z burn effect). It remains the Second Sea’s top sword for combos.
Easy Combo: Tap X > Z (breaks Instinct) > chain into fruits like Rumble or Godhuman. Trading value stays high at around 10M Beli or a Mythical fruit trade.
