The Undertale update in Verse Piece introduced Sans as a powerful new unlockable. However, obtaining him is a long process that involves boss farming, rare drops, and a hidden questline.
This guide explains every step clearly so you can unlock Sans without missing anything.
Where to Find the Sans NPC
To begin the unlock process, you must locate the Sans Seller NPC.
Start by going to Karakura Town, then enter the Turbo Tunnel. Inside this area, you will find the NPC who shows all the requirements needed to unlock Sans.
All Required Materials
Before you can obtain Sans, you must collect the following items:
- Mysterious Connection
- Grinning Void
- Blue Soul
- Bad Time Eye
- 3 Gaster Blasters
- 4 Pieces of the Void
- 20 KR Manifest
- 30 Eternal Bones
Most of these materials come from the Sans Boss.
How to Spawn the Sans Boss
To summon the boss, you must go to the Dungeon Cave.
Once there, defeat 20 Skeleton enemies. After killing enough skeletons, the Sans Boss will spawn automatically.
Sans Boss Phases and Drops
The boss has two phases, each with different drop pools.
Phase One Drops
The first phase can drop:
- KR Manifest
- Blue Soul
- Bad Time Eye
- Gaster Blasters
- Eternal Bones
This phase mainly provides basic materials.
Phase Two (Glitch Phase) Drops
The second phase unlocks additional rare drops:
- Grinning Void
- Pieces of the Void
- Blue Soul
- Bad Time Eye
- Gaster Blasters
- KR Manifest
- Eternal Bones
You must defeat this phase to obtain the rarest materials needed for Sans.
Titles and Accessories from the Boss
While farming, the boss can also drop:
- Lazy Bone Mask accessory
- Lazy Skeleton title (unlocked after obtaining Sans)
These are optional but useful rewards.
How to Get the Mysterious Connection Item
One required item, Mysterious Connection, does not drop from the boss.
It comes from a hidden questline involving a secret NPC named Gastra.
Step 1 — Find the Gastra NPC
Gastra appears in Wandon, but you cannot interact with the NPC immediately.
You must complete several objectives first.
Step 2 — Stability Test
The first requirement is a durability challenge.
You must:
- Tank a total of 1,000,000 damage
- Remain completely still
- Avoid dying during the process
Once completed successfully, Gastra interaction unlocks.
Step 3 — Memory Check Objective
Next, you must find the Shadowy Soul Orb.
This item:
- Spawns only at specific server times
- Appears inside the Endless Castle
After obtaining it, you can interact with Gastra again.
Step 4 — Final Interaction
To complete the quest:
Interact with Gastra at night. This grants:
- Mysterious Connection item
- Mystery Man title
This finishes the secret questline.
Unlocking Sans
After collecting all materials and completing the secret quest, return to the Sans NPC.
Once all requirements are met, Sans will be unlocked.