If you’re looking to unlock Zenitsu’s Thunder Sword in Legacy Piece, the process is actually pretty straightforward once you know where to go. The biggest challenge isn’t a difficult boss fight—it’s completing a few training objectives before you can claim the weapon.
This guide walks you through every requirement, where to start, and how to unlock the Thunder Sword as quickly as possible.
Thunder Sword Requirements
Before you can begin, make sure you meet these requirements:
- 1,000,000 Beli
- B Rank or higher
If you’re missing either requirement, focus on earning more Beli and increasing your rank before visiting the trainer.
Step 1: Visit Slayer Mansion
Travel to the Slayer Mansion.
Once you arrive, look for the Sleeping Slayer NPC and interact with them.
The NPC will explain the requirements needed to obtain the Thunder Sword, along with the training tasks you’ll need to complete.
Step 2: Defeat 75 Demon Slayers
Your first objective is simple:
Defeat 75 Demon Slayers.
This is the longest part of the quest, so finding an area with fast-respawning enemies will help you finish much quicker.
If you’re using a strong build or high-level fruit, clearing this requirement shouldn’t take too long.
Step 3: Complete the Small Gourd Training
After defeating the required enemies, return to the training area.
You’ll now need to:
Blow the Small Gourd 10 times.
Simply interact with the Small Gourd until you’ve completed all ten attempts.
Step 4: Blow the Medium Gourd
Next comes the Medium Gourd challenge.
Your objective is to:
Blow the Medium Gourd 25 times.
Continue interacting with it until the requirement is complete.
Step 5: Complete the Large Gourd Training
The final training objective is the Large Gourd.
You’ll need to:
Blow the Large Gourd 50 times.
Although it takes the longest of the three training stages, it’s simply a matter of repeating the interaction until you finish.
Step 6: Claim the Thunder Sword
After completing every requirement:
- Return to the Sleeping Slayer NPC.
- Interact with them once again.
If you’ve completed all the previous tasks and met the Beli and rank requirements, you’ll receive the Thunder Sword, inspired by Zenitsu.
Congratulations—you’ve officially unlocked the weapon.
Thunder Sword Unlock Checklist
Here’s a quick overview of everything you’ll need to complete:
| Requirement | Amount |
|---|---|
| Beli | 1,000,000 |
| Rank | B Rank or Higher |
| Demon Slayers Defeated | 75 |
| Small Gourd Training | 10 |
| Medium Gourd Training | 25 |
| Large Gourd Training | 50 |
Tips to Finish Faster
If you want to unlock the Thunder Sword as quickly as possible, these tips can save you some time:
- Farm enough Beli before visiting the Slayer Mansion.
- Reach at least B Rank beforehand so you don’t have to leave the quest midway.
- Defeat Demon Slayers in areas with quick respawns.
- Complete all three Gourd training stages in one visit.
- Return to the Sleeping Slayer NPC immediately after finishing the final objective.
Unlocking Zenitsu’s Thunder Sword in Legacy Piece doesn’t require rare drops or complicated boss mechanics. As long as you have 1,000,000 Beli, B Rank, and complete the Demon Slayer and Gourd training challenges, you’ll be able to claim the weapon without too much trouble.
If you’re working toward collecting every special weapon in Legacy Piece, this is one of the easier unlocks and well worth adding to your arsenal.