Gagin normally appears in a human skin that resembles a very tall man with spiked-up gray hair wearing battle armor. When he gets excited or angry enough, he begins to transform into his true self: a six-armed centaur with a horse head, sharp red fangs, and three horns emerging from his head. His mane, tail and ankles seem to have flames emerging from them.
Gagin is basically a hothead that loves a challenging fight. Most of Kokuboro's motives are secondary to him, he just wants to seek out and defeat strong opponents. He is at first disappointed when he sees that Karasumori's guardians are basically children, but quickly becomes excited when he sees their power. Though he is one of Kokuboro's best fighters, he allows his thirst for battle to overtake his senses. His office is full of various weapons, neatly arranged along the walls.
Kokuboro Leaders MeetingByaku, Gagin, Aihi, Shion, Hekian, and Koshu meet to discuss their progress. Byaku stresses the importance of time, as both Princess and the land are weakening. Gagin immediately suggests an all-out assault on Karasumori. Koshu disregards this idea at once, which angers Gagin to the point of transformation (Shion points out that his horns have grown). Koshu points out that even if they conquered Karasumori, they would be powerless during the day. Hekian agrees that they still don't know the most effective way to use the land's power. Gagin reluctantly gives in, but calls the waiting process stupid.
The Battle for KarasumoriDuring Kokuboro's first mass invasion of Karasumori, Gagin challenges Yoshimori, Tokine, and Gen. Despite already being more powerful than them, Gagin gets swept up in the battle and transforms into a fiery centaur. Gen has little choice but transform himself, and with support from Yoshimori and Tokine, gradually begins to overwhelm Gagin, seriously wounding him. But just as Gen is about to strike the finishing blow, Kaguro appears and brutally attacks Gen from behind, mortally wounding him. In the anime, Yoshimori defeats Gagin immediately afterward, but in the manga, Gagin and his forces retreat, and Gagin is not killed until the next invasion, where Masamori's Zekkai destroys half of his body.
Powers & Abilities
Fire Generation: Gagin has the ability to generate heat and fire. He commonly uses this fire to make fireballs of varying sizes and strength from his hands and fires them at his opponents. Gagin has a high level of internal heat that allows him to effortlessly drain the water from the Colorless Swamp by instantly evaporating it as he drinks it.
Flame Barrier: Gagin can surround his body in flames that are capable of incinerating anything around him. He does this frequently in battle, nearly every time that his temper flares. This can be used offensively and defensively. 
Demonic Aura: While in his true form, the power of Gagin's evil aura is immense and can be felt from far away.
Centaur Form: Gagin's true form is that of a demonic horned centaur with six arms. In this form he is far more powerful than in his human form, and uses enhanced versions of his general abilities. His fireballs in particular can be charged with enormous power, but take considerably longer to launch as a result.
- Flame Wings: Gagin is able to grow wings on his lower torso to achieve flight.
- Regeneration: Like most Ayakashi, Gagin displays some regenerative powers, which are boosted while in Karasumori.
- Gagin's name (牙銀) means silver fang.
- Gagin's true form seems to be an amalgamation of three mythological horse like creatures: a centaur, unicorn, and Pegasus.
- ↑ 1.0 1.1 1.2 1.3 1.4 Kekkaishi anime, Episode 26
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Kekkaishi anime, Episode 36
- ↑ 3.0 3.1 Kekkaishi anime, Episode 39
- ↑ 4.0 4.1 Kekkaishi manga, Chapter 80
- ↑ 5.0 5.1 5.2 5.3 Kekkaishi anime, Episode 37
- ↑ Kekkaishi manga, Chapter 95
- ↑ Kekkaishi manga, Chapter 103
|Leaders||Princess • Byaku|
|Division Leaders||Gagin • Sakon • Shion • Aihi • Koshu • Hekian • Kaguro|
|Subordinates||Sanan • Haroku • Sekia • Haizen • Kokuboro Trio • Kokuboro Maiden • Spider Goons • Hisui • The Spy|