To get the Rengoku Sword in Blox Fruits, follow these steps. First, make sure you have reached the Second Sea in the game. This is crucial as the Rengoku Sword is not available in the First Sea.
Next, travel to Ice Castle Island, located in the Second Sea. This island is where you’ll find the key and the chest containing the sword. The island is filled with NPCs and a boss that you’ll need to fight.
To obtain the Hidden Key, defeat the Arctic Warriors, Snow Lurkers, or the boss, Awakened Ice Admiral. The key has a low drop chance from the NPCs (0.5%) and a higher chance from the boss (5%). This means you might need to defeat several enemies before you get the key.
Once you have the Hidden Key, head to the Ice Castle Island’s chest location. Use the key to unlock the chest, and you’ll get the Rengoku Sword. Happy hunting!
For better chances, you can farm the NPCs or the boss multiple times. Server hopping can also help you find a server where the key drops more frequently. Watching YouTube guides or checking the Blox Fruits Wiki can provide additional tips and information.