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No special attributes, but powerful bullets: Asteroid.

Shiori Usami about Asteroid.[1]

Asteroid (通常弾(アステロイド) Asuteroido lit. Normal Bullet?) is a Gunner Trigger.


Asteroid appears as a straight, luminous trail once shot.


The origins of this Trigger are unknown. It was initially used exclusively in trion cube form, until firearms were invented.[2]


Asteroid is one of the mid-ranged options available to Border agents, which can be fired as a trion cube or through a firearm.[3] It has no special properties, moving in a straight line and not manifesting any particular effects on impact. As a consequence, it is slightly more powerful than the other Gunner Triggers. It is the best suited for concentrated fire and breaking Shields.[4][3]

As a Gunner Trigger, Asteroid is ordinarily less powerful than Attacker Triggers[5] and consumes more trion than the latter.[4] The higher the trion amount of the user, the more of it can be allocated to its three basic parameters, enhancing its performance.[citation needed] Osamu Mikumo's undivided Asteroid cube was perceived as harmless by Rabbit, to the point that it did not attempt to dodge it and simply let it bounce off the armor on its head,[6] whereas Chika Amatori's volley disintegrated the Trion Soldier.[7] If a bullet is powerful enough to break through a Shield, it will continue along its trajectory instead of dissipating upon impact;[8] on the other hand, Asteroid is generally unable to punch through matter that is not made out of trion, its effect being comparable to that of regular shells.[9] A safety mechanism is in place so that, should a bullet collide with a flesh and blood body, the owner will be knocked out from the pain and impact, without suffering any penetrating trauma.[10]

The lack of additional functions characteristic of this Gunner Trigger can be utilized strategically: by passing off special bullets as Asteroid, an opponent who is familiar with Border bullets can be surprised by the bullet's special properties.[11][12][13] With a large high trion discrepancy between the user and the target, a small number of skilled agents might see through the deception due to the special bullet's lower firepower.[14] Some degree of variation can be achieved by altering Asteroid's parameters.[15][16] Takuma Yuba is notable for sacrificing range and limiting his magazine to six bullets, leading to an increase in muzzle velocity and firepower[17] such that it can normally be blocked only with focused Shields or Full Guard.[8] With ordinary trion levels, Asteroid is the best Gunner Trigger to combine with Lead Bullet.[18]

Composite Bullets[]

Components Name Image Description
Asteroid + Asteroid Gimlet
(徹甲弾(ギムレット) Gimuretto lit. Armor-Piercing Bullet?)[19]
Izumi Gimlet.gif Gimlet doubles the specs of its individual components.[20] Increasing its speed and penetration capabilities.
Asteroid + Viper Cobra
(コブラ Kobura?)[21]
No Image Available.png The properties of this composite bullet are currently unknown.
However, theoretically it would combine Asteroid with Viper's trajectories property, possibly making the bullets penetrate more easily.
Asteroid + Hound Unknown No Image Available.png The properties of this composite bullet are currently unknown.
However, theoretically it would combine Asteroid with Hound's tracking property, possibly making the bullets penetrate more easily.
Asteroid + Meteor Unknown No Image Available.png The properties of this composite bullet are currently unknown.
However, theoretically it would combine Asteroid with Meteor's explosive property, possibly making the bullets penetrate more easily.


Image Name Description
Slow buck shot.png Slow Buckshot
(低速散弾(ていそくさんだん) Teisoku Sandan?)[22]
A technique in which the user, after dividing their trion cube, discharges the fragments by allocating 70% of the trion to power, 29.9% to range, and 0.1% to speed. The slow but powerful bullets occupy a relatively wide area in front of the user, making it difficult for an enemy to maneuver or attack without coming in contact with them. Osamu Mikumo has shown to be the only user.[15]


See also: Asteroid Users

Asteroid is the most popular Gunner Trigger, with 42 known agents having at least one Asteroid chip in their Trigger Set, 19 of which fire it through assault rifles, 12 in the form of a trion cube, 10 through handguns, two through shotguns and one through a minigun.[23] The latter is used by Reiji Kizaki, who also utilizes an assault rifle,[24] with no. 1 Gunner Kazuma Satomi channeling the bullet through one handgun and one assault rifle.[25] The Asteroid user with the most points is no. 1 Shooter and no. 2 solo combatant[26] Masataka Ninomiya.[27] Asteroid is also used by an unknown number of trainees, and possibly by agents who do not take part in Rank Wars.


  • All known All-Rounders have Asteroid in their Trigger set.[23]
  • This Trigger's abilities were replicated by Yūma's Trigger from Shūji Miwa's Asteroid to create the Bolt seal.[28]
  • It is currently unconfirmed whether, on top of boasting greater firepower, Asteroid is ordinarily set to be faster and have more range than special bullets. Using Lead Bullet with any other Gunner Trigger was stated to lead to diminished range and muzzle velocity,[18] although this may be due to the Optional Trigger siphoning trion from those two parameters as a consequence of the quantity allocated to firepower being insufficient to manifest the weights.


  1. 1.0 1.1 World Trigger Manga Chapter 29 (p. 3)
  2. Daisuke Ashihara: Q156: Are Shooters derived from Gunners? Who created the Shooter position and how did it happen? A: The order is that Shooter came first. There are those suited for handling cube bullets and those who aren’t, so gun triggers were developed so that anyone can use bullets with a high degree of accuracy, and Gunners were derived.
    Source: Border Briefing File, Question 156, p. 305
  3. 3.0 3.1 World Trigger MangaBorder Briefing File (p. 214)
  4. 4.0 4.1 Gunner Triggers, Volume 4, Chapter 30
  5. World Trigger Manga Chapter 107 (p. 14)
  6. World Trigger Manga Chapter 67 (p. 10-11)
  7. World Trigger Manga Chapter 67 (p. 16-17)
  8. 8.0 8.1 World Trigger Manga Chapter 187 (p. 6)
  9. World Trigger Manga Chapter 89 (p. 5)
  10. World Trigger Manga Chapter 119 (p. 5)
  11. World Trigger Manga Chapter 155 (p. 16)
  12. World Trigger Manga Chapter 188 (p. 14)
  13. World Trigger Manga Chapter 195 (p. 10-14)
  14. World Trigger Manga Chapter 178 (p. 12)
  15. 15.0 15.1 World Trigger Manga Chapter 36 (p. 14)
  16. World Trigger Manga Chapter 100 (p. 10)
  17. World Trigger Manga Chapter 182 (p. 4)
  18. 18.0 18.1 World Trigger Manga Chapter 120 (p. 11)
  19. World Trigger Manga Chapter 68 (p. 2)
  20. Daisuke Ashihara: Q142: What abilities does the "Gimlet" that Izumi used in Volume 8 have? A: By doubling the structure of the bullet, penetration power is increased; it is used to breach Shield or firm armor and cause damage.
    Source: Border Briefing File, Question 142, p. 303
  21. Daisuke Ashihara: Q143: Please tell us if there are any other composite bullets besides Tomahawk and Gimlet. A: There are ones like Meteor + Hound’s "Salamander", Asteroid + Viper’s "Cobra", Hound + Hound’s "Hornet" etc.
    Source: Border Briefing File, Question 143, p. 304
  22. World Trigger Manga Chapter 68 (p. 17)
  23. 23.0 23.1 World Trigger MangaBorder Briefing File
  24. World Trigger MangaBorder Briefing File (p. 91)
  25. World Trigger MangaBorder Briefing File (p. 60)
  26. World Trigger Manga Chapter 103 (p. 14)
  27. Daisuke Ashihara: Q240: Exactly what numbers are used to decide the separate position ranking and the solo overall ranking? Is it the highest solo points? Or the total points of all the weapons? A: It is the highest of the solo points. The solo overall ranking is decided from all the weapon points of all the agents based on who has the highest. From all of the Shooters, Ninomiya’s Asteroid points are the highest -> Shooter ranking no. 1. From all weapons of all of the agents, Tachikawa’s Kogetsu points are the highest -> solo overall no. 1, like that. If there was a total point ranking then Reiji would probably be no. 1.
    Source: Border Briefing File, Question 240, p. 317
  28. Yūma's Seals, Volume 2, p. 170


Border Triggers
Basic Equipment Bail OutRadarTrion Body
Attacker Kogetsu (Kogetsu: Spear) • Raygust (Shield Mode) • ScorpionSōgetsu (Axe)
Gunner AsteroidCobraGimletHornetHoundMeteorSalamanderTomahawkViper
Firearms Assault Rifle • Grenade Launcher • Handgun • Minigun • Shotgun
Sniper EgretIbisLightning
Defense EscudoShield (Fixed Mode/Full Guard)
Trap Switchbox
Optional BagwormBagworm TagChameleonConnectorDummy BeaconEnhanced RadarFull ArmsGeistGen'yōGrasshopperIdatenLead BulletMakōSenkūSilencerSpiderStarmakerTeleporterThrusterTimer
Prototypes ConnectorDummy BeaconFull ArmsGeistIdatenMakōTeleporterTimer
Black FūjinTsukihiko Amō's Black TriggerYūma's Black Trigger