Ballistics for which you can choose the trajectory: Viper.

Shiori Usami about Viper.[1]


Izumi Viper anime


Kanji 変化弾
Organization BrDr Border
Type White trion Normal
Classification Viper icon Gunner
- Preset trajectories
First Appearance
Manga Chapter 29
Anime Episode 15

Viper (変化弾(バイパー) Baipā?, lit. Changing Bullet) is a Gunner Trigger.


Once shot, Viper appears as a luminous trail that, due to its properties, often resembles a zigzag. The size of each bullet is directly proportional to the amount of trion the user has. Gunners fire Viper bullets through different types of gun-shaped Triggers, whereas Shooters form a trion cube that can be divided in smaller regular polyhedrons, their size and shape depending on how many are created at once.


The origins of this Trigger are unknown. It was first used by Shooters only, until firearm Triggers were invented.[2]

Abilities Edit

The main feature of Viper is that its projectiles can travel along trajectories the user has programmed in their mind before shooting.[3] This property gives it more complicated flight paths than any other bullet Trigger, including Hound, but its destructive power is lower than Asteroid's.[4] Although the number of patterns available is theoretically infinite, due to Viper being the most difficult Gunner Trigger to master[5] agents learn and preprogram only a few useful trajectories.[3] Two of them are Pattern A and Pattern B:[3] Pattern A causes the bullets to scatter after a few meters before converging on one point,[3] allowing the user to hit enemies hiding behind flat, durable shields;[6] as in Pattern A, in Pattern B the bullets start moving in a straight line before fanning out in multiple directions.[3] This set of flight paths makes it possible to quickly target multiple opponents,[7] shoot behind corners[8] and to use feints by pretending to attack one enemy and then redirecting the bullets to hit other targets.[9]

Certain Shooters, however, are capable of creating new patterns each and every time they use this Trigger.[3] To do so, a keen sense of spatial awareness and the skill to visualize something that does not yet exist are required.[10] Rei Nasu and Kōhei Izumi are the only two users who can efficiently exploit this capacity in combat.[3] Hyuse was hinted to be able to do the same, although he is still inexperienced.[5] This capacity grants them unparalleled flexibility and permits them to fight efficiently regardless of the presence of obstacles,[11] as they can simply program the bullets to avoid them.[12] They can even use them to their advantage, curving the flight path of the projectiles out of sight so as to lead the opponent to miscalculate their position.[13] Other tricks at their disposal include the ability to target multiple enemies with the same trajectory by making it go through multiple of them, so that even if the first dodges the attack, another will be hit.[9] Since the bullets can change pattern at any moment, avoiding them is very difficult if the user can predict how the opponent will move. This strategy can be used to suddenly focus a seemingly scattershot attack on only one point, tricking the target into expanding and hence weakening their defense before breaking through with concentrated fire.[14] A user who can control Viper freely can employ luring tactics to lead the enemy into thinking they are vulnerable after shooting, whereas they have directed their bullets to come back and bombard the area around them.[15]

When combined with Meteor,[16] Viper creates the composite bullet Tomahawk, which retains the explosive properties of the former and the ability to travel along predetermined patterns of the latter.[17] The merging of Asteroid and Viper takes the name of Cobra.[18] Its characteristics are still unknown.


Name Description
Birdcage anime Birdcage (鳥籠(とりかご) Torikago?)[19] By firing Viper through both the Main and the Sub, the user unleashes a multidirectional attack to simultaneously target all enemies within their line of sight or visible on Radar, proving themselves a threat even when surrounded.[19] The only known user of this tactic is Rei Nasu.[19]


See also: Viper Users

With merely 8 known users, 3 Shooters and 5 Gunners, Viper is by far the most unpopular Gunner Trigger. Among the Gunners, 3 channel it through an assault rifle and 2 through at least one handgun.[20] The two agents who can use this Trigger to its full potential, Kōhei Izumi and Rei Nasu,[3] are Shooters. It should be noted that the list above excludes those members of branches who do not participate in rank battles.[21]


  • Like other Gunner Triggers, Viper may have been named after a missile, the AGM-80 Viper, whose system offered fire-and-forget performance. Alternatively, it may be derived from a rocket, the FGR-17 Viper.
    • The viper is a family of venomous snakes. Snakes have many vertebrae which allow for increased flexibility, which is similar to how this Trigger is flexible in changing trajectory.


  1. 1.0 1.1 World Trigger Manga Chapter 29 (p. 4)
  2. World Trigger MangaBorder Briefing File (p. 305)
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 World Trigger Manga Chapter 97 (p. 13)
  4. World Trigger Manga Chapter 30 (p. 19)
  5. 5.0 5.1 World Trigger Manga Chapter 162 (p. 15)
  6. World Trigger Manga Chapter 58 (p. 4)
  7. World Trigger Manga Chapter 79 (p. 13)
  8. World Trigger Manga Chapter 125 (p. 15)
  9. 9.0 9.1 World Trigger Manga Chapter 126 (p. 11)
  10. World Trigger MangaBorder Briefing File (p. 304)
  11. World Trigger Manga Chapter 101 (p. 6)
  12. World Trigger Manga Chapter 97 (p. 12)
  13. World Trigger Manga Chapter 59 (p. 12)
  14. World Trigger Manga Chapter 100 (p. 8-9)
  15. World Trigger Manga Chapter 102 (p. 16)
  16. World Trigger Manga Chapter 101 (p. 9)
  17. World Trigger Manga Chapter 101 (p. 8)
  18. World Trigger MangaBorder Briefing File (p. 304)
  19. 19.0 19.1 19.2 World Trigger Manga Chapter 100 (p. 6)
  20. World Trigger MangaBorder Briefing File
  21. World Trigger Manga Volume 18


e - d - vBorder Triggers
Basic Equipment Bail OutRadarTrion Body
Attacker Kogetsu (Kogetsu: Spear) • Raygust (Shield Mode) • ScorpionSōgetsu (Axe)
Gunner Asteroid • Cobra • Gimlet • Hornet • HoundMeteorSalamanderTomahawkViper
Firearms Assault Rifle • Grenade Launcher • Handgun • Minigun • Shotgun
Sniper EagletIbisLightning
Defense EscudoShield (Affixed Mode/Full Guard)
Trap Switchbox
Optional Bagworm • Bagworm Tag • ChameleonConnector • Dummy Beacon • Enhanced Radar • Full ArmsGeistGen'yōGrasshopperIdatenLead Bullet • Makō • Senkū • Silencer • SpiderStarmakerTeleporterThruster • Timer
Prototypes Connector • Dummy Beacon • Full ArmsGeistIdaten • Makō • Teleporter • Timer
Black Fūjin • Tsukihiko Amō's Black Trigger • Yūma Kuga's Black Trigger
Community content is available under CC-BY-SA unless otherwise noted.