Shadow Crystal

Shadow Crystals, so called because you can only see their shadow.

Seam, Chapter 2

The Shadow Crystal (JP: シャドウジェム Shadow Gem) is a recurring secret Key Item found across the first five Chapters of Deltarune.

Acquisition

One can be obtained after defeating a Shadow Crystal boss. Once the player has a SAVE that has a Shadow Crystal, the Chapter Select indicates which SAVE slot has it on the bottom-right of the menu.

Afterwards, the earned Shadow Crystal and the last-earned equipment can be shared to other SAVE files that are in the same slot and on a later Chapter once the boss is defeated, and any other SAVE files on a later Chapter if there exists vacancy to rearrange SAVE file slots or save to multiple slots. It can be found in a hole in the cliffs, left of Castle Town.

Usage

For Seam's commentary, see Seam § Shop dialogue.

Shadow Crystals can be given to Seam in Castle Town, who provides commentary and occasional hints depending on the Chapter. They offer to create something if all five are collected via Completion FILEs.

Using the Shadow Crystal in a Dark World seemingly shows Kris the Light World's equivalent of the current location. This inventory check can only be done once, and cannot be repeated.

If a Shadow Crystal is carried over from a previous Chapter, the Use message for Chapter 3 can appear before the Chapter's Shadow Crystal is obtained, which foreshadows Tenna's defeat at the Knight's hands.

Main story

In Chapter 2, Seam hints that more Shadow Crystals can be earned from difficult enemies. Upon obtaining a second Shadow Crystal, Seam tries to offer a Shadow Mantle to assist the party for the upcoming Shadow Crystal boss, but is unable to find it.

In Chapter 5, Seam explains that Shadow Crystals form when a passion is shattered, and is the power of "lost dreams". Seam describes the results of their utilization as being "very, very, interesting", and believe that Kris will find what is done with them to be "entertaining".

The Glass (JP: ガラス) is the Light World form of the Shadow Crystal, separate from the Ball of Junk. It cannot be dropped, as "the thought of discarding it felt very wrong". Using the Glass makes Kris see through it, either seeing Susie glaring at them if she is following in Chapter 2, Noelle leaning against them and whispering in Noelle's House in Chapter 4, or otherwise seeing through their hand.

Flavor text

Using the Glass in the Light World shows an illusion of unknown meaning. Both of these effects quickly pass, and cannot be repeated.

Shadow Crystal

• You held the crystal up to your eye.
  • For some strange reason, for just a brief moment... [First use]
    • You thought you saw toys strewn on the floor. [Card Kingdom]
    • You thought you saw the computer lab. [Cyber World]
    • You thought you saw the television get smashed to pieces. [TV World]
    • You thought you saw the lobby of the church. [Dark Sanctuary]
    • ...but, it must've just been your imagination. [Follow-up]
  • [Flower Kingdom Garden]
    • For some strange reason, for a brief moment, it looked like...
    • Everyone else disappeared...
    • ... and you saw Noelle smiling at you, with arms full of flowers.
  • ... but nothing happened. [Second use, or Castle Town]
• It doesn't seem very useful. [Subsequent uses]

In the Dark Sanctuary, the Shadow Crystal interacts with the prophecies appearing throughout.

Dialogue when used in a room with a prophecy tapestry

• You held the crystal up to your eye.
• For some strange reason, no matter how you look...
• The prophecy's text does not warp in the crystal's lens.

Dialogue when used in the room with the Last Prophecy

• You held the crystal up to your eye.
• For some strange reason...
• The prophecy's text does not warp in the crystal's lens.
• You shook the crystal...
• However, nothing changed.

Glass

• You looked through the glass.
  • For some strange reason, for just a brief moment... [First use]
    • You thought you saw through your hand. [Default]
    • You thought you saw Susie glaring at you, coldly... [Followed by Susie, Chapter 2]
      • But when you moved the glass away,
      • You see her looking at you, smiling and making a rude gesture.
    • You thought you saw Noelle close against you, whispering. [Noelle's House, Chapter 4]
      • You put the glass to your ear...
      • ... of course, that didn't do anything...
    • You thought you saw your mother holding someone else. [Toriel's House, Chapter 5]
    • You thought you saw Susie in a far-off window, unkempt and glaring. [With party members, Chapter 5]
  • ... but nothing happened. [Second use]
• You held the crystal up to your eye. [First use, Chapter 3; Unused]
  • For some strange reason, for just a brief moment...
  • You thought you saw Undyne frozen in ice.
• It doesn't seem very useful. [Subsequent uses]
• (You didn't quite understand why...) [Attempting to drop, Chapters 1&2]
  • (But, the thought of discarding it felt very wrong.)
• (For some reason you felt like if you throw it away...) [Attempting to drop, Chapters 4&5]
  • (It would be like throwing away someone's... ???)
  • (... But you didn't fully understand it.)

Creation and development

In January 2026, Toby Fox teased a portion of Seam's Chapter 5 dialogue regarding the Shadow Crystal, though it was cut-off on the translation sheet.

Gallery

• 
  Shadow Crystal received from defeating Jevil
• 
  Shadow Crystal received from defeating Spamton NEO
• 
  Defeating Spamton NEO in the Weird Route for a Shadow Crystal
• 
  Shadow Crystal received from defeating the Knight
• 
  Shadow Crystal received from defeating the Hammer of Justice
• 
  Shadow Crystal received from defeating Pink
• 
  Shadow Crystal received from the Castle Town cliff

Trivia

• There exists a currently-unused item called the PureCrystal. Its item description, "The shadow purified by the cat", may suggest that it is a Shadow Crystal which was purified by Seam.
• A "peculiar book" that can be found in the 2nd Sanctuary mentions a "fallen star" making "rivers with its tears" until something that "looked like glass" was formed out of the "bitter water", suggesting a possible connection to Shadow Crystals.
• As of Version 1.04, it is impossible to see the drop text in Chapter 4 on PC because the code that checks whether a Light World item is a weapon or not will always at least return the ID for the Pencil, causing all items to display "(Recently, seems like weapons can't be thrown away so easily.)" when attempting to drop them in Chapter 4.
• In the Japanese version, for Seam's Chapter 4 dialogue that is triggered if the first two Shadow Crystals were already given to them, but the party was defeated by the Knight while also having the Shadow Mantle, the Shadow Crystal's Japanese name, シャドウジェム ("Shadow Gem"), is mistranslated as シャドウクリスタル ("Shadow Crystal").

Version history

Game edition	Version tag	Changes
Chapter 1&2 Demo	v1.06	Allowed the Glass to properly appear in the Light World inventory if Kris has a Shadow Crystal.
	v1.07	Jevil gives the Shadow Crystal immediately when defeated. New flavor text was added for using the Shadow Crystal or Glass in Chapter 1.
	v1.19	Introduced an indicator of attained Shadow Crystals per SAVE file and Chapter to the Chapter Select screen.
Deltarune	v1.00	Collecting Jevil's Shadow Crystal and one equipment from the cliff of Castle Town requires Jevil has been defeated in the corresponding save slot, instead of any one.