Wiseman holding Virus Cores in The World.

"Virus Cores are the key to breaking through protective barriers. Of course, Virus Cores are useless to those who don't have the Bracelet"

Virus Cores (ウィルスコア) are objects found in The World, The World R:2, and The World R:X.



In The World, Virus Cores A-L could be extracted from Data Bugs, removing their irregular stats. Once obtained, wielders of the Twilight Bracelet could use them to rewrite and remove safety locks on a Chaos Gate, granting access into protected areas. Later in the story, as the infection worsened, Virus Cores became easier to find, appearing in rooms with barrels and treasure chests. Virus Cores M-Z are reserved for story purposes.

Delta Server and Theta Server

(With some exceptions)
  • Small-Size Monsters: Virus Core A
  • Medium-Size Monsters: Virus Core B
  • Large-Size Monsters: Virus Core C

Lambda Server (Battle Level 30 and below)

(With some exceptions)
  • Small-Size Monsters: Virus Core A
  • Medium-Size Monsters: Virus Core B
  • Large-Size Monsters: Virus Core C

Lambda Server (Battle Level 31 and up)

(With some exceptions)
  • Small-Size Monsters: Virus Core D
  • Medium-Size Monsters: Virus Core E
  • Large-Size Monsters: Virus Core F

Sigma Server

(With some exceptions)
  • Small-Size Monsters: Virus Core G
  • Medium-Size Monsters: Virus Core H
  • Large-Size Monsters: Virus Core I

Omega Server

(With some exceptions)
  • Small-Size Monsters: Virus Core J
  • Medium-Size Monsters: Virus Core K
  • Large-Size Monsters: Virus Core L

.hack//Legend of the Twilight Manga

In the manga Balmung gives them to Shugo at the end of the third volume so he Rena and Zefie can reach the field where Aura is.

A Virus Core in The World R:2


In Roots, Virus Cores appear to only be found in Lost Grounds and are known as "the item that cannot be used". But when all six cores are collected, they can be used in the Lost Ground Coite-Bodher to warp to a secret part of the area atop a floating castle. However, it is later revealed that this was part of an elaborate trap set for Ovan by the system administrator Yata.


Members of the Seventh Division of Moon Tree find a large number of Virus Cores at the bottom of a Christmas event area.

.hack//G.U. Games

In Volume 3, Virus Cores can be used to power up the Lost Weapons. They are obtained by using Avatar Awakening on monsters and certain players. The amount of Cores gained varied depending on the size of the opponent, from 1 to 3. Once all lost weapons are upgraded to their max, Zelkova sends you a message, revealing that he is your "unseen ally" and saying you probably have left over Virus Cores, then offers to trade them for rare Text and Books. Data Seeds, items very similar to Virus Cores (especially in use compared to the original games), also make an appearance and can be data drained from AIDA.


In Link, Virus Cores act much like they did in the G.U. games, but instead of upgrading weapons, they allow Tokio to alchemize rare items, Virus Cores, and even a PC's job rank, possibly allowing them to gain their Xth Form. Virus Cores are obtained by opening breakable objects, and preforming Cross Rengeki. Virus Cores A - Z can be obtained through story-mode, while Virus Core Ω can only be obtained through Link Play or special means.

The World R:1 - 2014

  • Small-Size Monsters: A, D, G, J
  • Medium-Size Monsters: B, E, H, K
  • Large-Size Monsters: C, F, I, L

The World R:2 - 2017

  • Small-Size Monsters: G, J, M, P, S, V
  • Medium-Size Monsters: H, K, N, Q, T, W
  • Large-Size Monsters: I, L, O, R, U, X

The World R:X - 2020

  • Small-Size Monsters: S, V, X
  • Medium-Size Monsters: T, W, Y
  • Large-Size Monsters: U, X, Z