How to Get All Demon Slayer Swords Reign Piece (March 2026) Complete Guide

Shruti Agarwal
January 27, 2026
RobloxGaming

Looking to master the Demon Slayer update in Reign Piece? You’ve come to the right place! The Demon Slayer swords are among the most powerful weapons in Reign Piece 2026, offering incredible damage output and unique abilities that will transform your combat experience. Whether you’re a seasoned player or just starting your Demon Slayer journey, this comprehensive guide will walk you through every step needed to obtain all three legendary swords: Zenitsu’s Thunder Breathing blade, Kaigaku’s Black Lightning weapon, and Tengen Uzui’s flashy Sound Breathing cleavers.

Sword Name	Main Location	Key Requirement	Difficulty
Zenitsu Sword	Zenitsu Boss Area	Sleepwalker Trait	Medium
Kaigaku Sword	Infinity Castle Raid	Hybrid Race	Hard
Tengen Uzui Sword	Infinity Castle Raid	High-level gear	Very Hard

In this guide, I’ll break down everything you need to know about accessing Tengen’s Hideout Island, obtaining the crucial Infinity Castle Key, mastering the challenging Infinity Castle Raid, and efficiently farming each sword. Let’s dive in and get you equipped with the most powerful weapons in Reign Piece!

How to Get All Demon Slayer Swords in Reign Piece?

Getting Started: Tengen’s Hideout Island

Before you can even think about obtaining Demon Slayer swords, you need to access the main hub for all Demon Slayer content. All Demon Slayer sword NPCs are located on Tengen’s Hideout Island, which serves as your central base for the entire Demon Slayer progression path.

Prerequisites for Tengen’s Hideout Island:

Reach mid-to-late game progression
Complete basic story quests
Have adequate combat stats (recommended: Level 500+)
Possess basic gear for boss fights

This island is crucial because it houses all the weapon sellers, progression NPCs, and quest givers for the Demon Slayer content. Make sure you can comfortably fight mid-to-late-game bosses before attempting to unlock any Demon Slayer swords, as the content is designed for experienced players.

The Infinity Castle Key: Your Gateway to Advanced Content

The Infinity Castle Key is absolutely essential for accessing the Infinity Castle Raid, which is mandatory for obtaining two of the three Demon Slayer swords (Kaigaku and Tengen Uzui). Without this key, you’ll be locked out of the most rewarding Demon Slayer content.

Two Methods to Obtain the Infinity Castle Key:

Random Drops from Zenitsu Boss
- Chance to drop as a rare reward
- Estimated drop rate: 1-2%
- Can farm multiple times per day
Crafting at Shibuya Crossing Island
- Requires Infinity Castle Key Fragments
- Need 10 fragments to craft one key
- Fragments drop from Zenitsu Boss more frequently

Pro Tip: I recommend farming the Zenitsu Boss extensively early on, as this serves a dual purpose – you get materials for Zenitsu’s sword AND potentially the Infinity Castle Key or fragments needed for crafting.

Understanding the Infinity Castle Raid

The Infinity Castle Raid is the centerpiece of Demon Slayer content and arguably the most challenging raid in Reign Piece 2026. This raid functions like a dungeon with one critical rule: you only get one life. If you die during the raid, the run ends immediately, and you’ll need another Infinity Castle Key to try again.

Key Features of Infinity Castle Raid:

Single-life mechanic (no respawns)
Multiple Demon Slayer-themed bosses
High-level rewards and materials
Team-based content (solo possible but extremely difficult)
Time-limited runs (typically 30 minutes)

Recommended Team Composition:

Tank: High HP/Defense build
DPS: Damage-focused players (2-3)
Support: Healer/Buffer if available

My Strategy: Always bring friends or join a Discord group for Infinity Castle runs. Going solo is possible with maxed gear and skill, but you’ll waste precious keys and time. A coordinated team can clear the raid 3-4x faster than solo attempts.

Complete Demon Slayer Sword Guides

1. Zenitsu Sword Guide – The Thunder Breathing Blade

The Zenitsu sword is typically the first Demon Slayer weapon players aim for, and for good reason. Not only is it an excellent weapon in its own right, but obtaining it also unlocks access to later content and provides materials needed for the Infinity Castle Key.

Requirements to Get Zenitsu Sword:

12 Thunder Breathing Cores – Primary material from Zenitsu Boss
3 Static Soul Orbs – Rare drop from Zenitsu Boss
Sleepwalker Trait – Must be unlocked before claiming the sword

Farming Strategy: The Zenitsu Boss can be spawned using crystals (available from various merchants). Here’s my optimized farming approach:

Preparation Phase:
- Stock up on spawning crystals (50+ recommended)
- Equip your best AOE damage weapons
- Bring healing items and buffs
- Set up a farming rotation with friends if possible
Boss Battle Tips:
- Zenitsu uses lightning-based attacks
- Bring lightning resistance gear if available
- Focus on dodging his special moves
- Use burst damage during his vulnerable phases
Drop Optimization:
- Higher difficulty = better drop rates
- Team farming increases quantity of drops
- Consider using luck-boosting accessories
- Farm during server events for bonus rates

Expected Farming Time: 2-4 hours of continuous farming (varies by luck and drop rates)

Zenitsu Sword Stats & Abilities:

High base damage with lightning element
Special attack: Thunder Clap and Flash
Excellent for crowd control
Scales well with Haki abilities

2. Kaigaku Sword Guide – The Black Lightning Weapon

The Kaigaku sword represents a significant power upgrade from Zenitsu’s blade and is obtained entirely through the Infinity Castle Raid. This weapon is perfect for players who have mastered the basics and are ready for endgame content.

Requirements to Get Kaigaku Sword:

15 Black Lightning Cores – Dropped by Kaigaku boss in Infinity Castle
1 Demon Blood – Rare drop from Kaigaku (5% chance)
Hybrid Race – Must be unlocked before claiming the sword

Infinity Castle Raid Strategy for Kaigaku Materials:

Phase 1: Preparation

Ensure you have Hybrid Race unlocked (this can take time)
Bring your best gear and consumables
Coordinate with your team before entering
Have backup Infinity Castle Keys ready

Phase 2: The Raid

Clear initial waves of demons
Defeat mini-bosses to progress
Reach Kaigaku’s chamber
Prepare for the intense boss battle

Phase 3: Kaigaku Boss Fight

Kaigaku uses enhanced lightning attacks
More aggressive than Zenitsu
Requires perfect timing and dodging
Team coordination essential for success

Pro Tips for Kaigaku Sword:

Practice the raid multiple times before attempting serious runs
Learn Kaigaku’s attack patterns thoroughly
Save your best abilities for his final phase
Consider recording your attempts to analyze mistakes

Expected Farming Time: 5-10 successful raid runs (varies by team skill and drop rates)

Kaigaku Sword Features:

Superior damage to Zenitsu sword
Black lightning effects (purely cosmetic but awesome)
Enhanced critical hit chance
Better scaling with advanced Haki

3. Tengen Uzui Sword Guide – The Sound Breathing Cleavers

Tengen Uzui’s sword is arguably the most visually impressive and technically challenging Demon Slayer weapon to obtain. These dual cleavers require the most extensive farming due to the sheer number of materials needed and the difficulty of the content.

Requirements to Get Tengen Sword:

20 Flash Sigils – Dropped by Tengen Boss in Infinity Castle
10 Explosive Rhythm Fragments – Common drop from Tengen Boss
2 Uzui Clan Relics – Ultra-rare drop (1% chance)

Advanced Farming Strategy:

Optimizing Your Infinity Castle Runs:

Speed Running Techniques:
- Learn optimal routes through the castle
- Skip unnecessary enemies when possible
- Use movement abilities effectively
- Coordinate team positioning
Tengen Boss Mastery:
- Tengen uses sound-based attacks
- Requires precise timing for dodges
- Has multiple phases with different patterns
- Team positioning crucial for survival
Drop Rate Maximization:
- Run with full team of 4 players
- Use any available luck boosts
- Farm during special events
- Maintain kill streaks for bonus drops

Time Investment Expectation: This sword typically takes the longest to farm – expect 15-20 successful raid runs minimum, possibly more depending on your luck with Uzui Clan Relics.

Tengen Sword Special Features:

Dual-wielding mechanics
Sound-based visual effects
Highest base damage among Demon Slayer swords
Special abilities with area-of-effect damage
Perfect for both PvE and PvP content

Advanced Farming Strategies and Pro Tips

Efficient Resource Management

Key Conservation Strategies:

Never enter Infinity Castle unprepared
Save keys for organized team runs
Practice with cheaper content first
Use training modes to learn boss patterns

Inventory Optimization:

Keep essential materials easily accessible
Use storage for excess items
Track your progress toward each sword
Trade duplicate materials with teammates

Team Building and Coordination

Finding Reliable Teammates:

Join official Reign Piece Discord servers
Use Reddit communities for LFG (Looking for Group)
Build relationships with regular players
Create dedicated farming groups

Role Specialization:

Designate tank, DPS, and support roles
Practice team compositions
Develop communication strategies
Share materials fairly among team members

Common Mistakes to Avoid

Beginner Errors:

Attempting raids undergeared
Wasting keys on solo attempts
Not unlocking required traits/races first
Ignoring team coordination

Advanced Mistakes:

Rushing through content without learning mechanics
Hoarding materials instead of progressing
Neglecting to upgrade other gear
Burning out from excessive grinding

Are Demon Slayer Swords Worth the Grind?

Absolutely, yes! All Demon Slayer swords offer significant advantages that make the extensive farming worthwhile:

Combat Advantages:

Superior damage output compared to standard weapons
Unique visual effects and animations
Excellent scaling with game progression systems
Special abilities that enhance combat effectiveness

Meta Relevance:

Top-tier weapons for raid content
Excellent for PvP combat scenarios
Great for farming and grinding efficiency
Status symbols within the community

Long-term Value:

Remain relevant through game updates
Essential for endgame content
High trade value if you decide to switch weapons
Unlock advanced build possibilities

When combined with advanced Haki stages, Demon Slayer swords become some of the strongest weapons currently available in Reign Piece 2026. If your goal is endgame combat or efficient farming, collecting all Demon Slayer swords is absolutely worth the effort.

FAQ

Why can’t I access Tengen’s Hideout Island?

Ensure you’ve completed the main story quests up to the Demon Slayer update. You need to be at least level 400 and have defeated the previous major boss.

The Zenitsu Boss isn’t spawning. What’s wrong?

Check that you have the correct spawning crystals and are in the right location. Also ensure the server isn’t experiencing any issues or maintenance.

I died in Infinity Castle Raid. Do I lose everything?

You lose the run and any progress in that specific raid attempt, but you keep all materials and items you’ve already collected from previous runs.

Can I trade Demon Slayer swords with other players?

Currently, Demon Slayer swords are soulbound to the character that obtains them. However, you can trade excess materials with teammates.

What’s the best order to obtain the swords?

I recommend: Zenitsu → Kaigaku → Tengen. This progression follows the natural difficulty curve and ensures you have the keys needed for advanced content.

How many Infinity Castle Keys do I need?

Plan for at least 25-30 keys total if you want all three swords, accounting for failed runs and bad luck with drops.

Can I get Demon Slayer swords without being in a guild?

Yes, but it’s significantly harder. You can use public Discord servers and LFG channels to find groups.

Do Demon Slayer swords expire or become outdated?

These weapons are designed to remain relevant throughout the current game meta and typically receive buffs rather than nerfs in updates.

What happens if I die during a boss fight in Infinity Castle?

The entire raid run ends, and you’ll need to use another key to try again. This is why team coordination is so important.

Are there any shortcuts or exploits to get these swords faster?

No legitimate shortcuts exist. Any methods claiming instant acquisition are likely scams or exploits that could result in account suspension.

Conclusion and Next Steps

Unlocking every Demon Slayer sword in Reign Piece is undoubtedly a grind-heavy process, but it’s also one of the most rewarding progressions in the game. From farming Zenitsu to surviving intense Infinity Castle runs, each step pushes you toward endgame strength and mastery.

Your Action Plan:

Immediate Steps: Access Tengen’s Hideout Island and start farming Zenitsu Boss
Short-term Goals: Obtain Zenitsu sword and craft Infinity Castle Key
Medium-term Objectives: Master Infinity Castle Raid and get Kaigaku sword
Long-term Achievement: Complete your collection with Tengen Uzui’s dual cleavers

Remember to take your time, farm smart, and eventually you’ll have all Demon Slayer weapons sitting comfortably in your inventory, ready to dominate any content Reign Piece throws at you.

Happy hunting, and may your blade be ever sharp in the world of Reign Piece!