Trigger is part of Matheus's pack and a former pet dog.
Ginga Densetsu Weed: OrionEdit
He tries to attack Masamune while he recovers from his wounds in a hot spring, believing he can take on a dog smaller and injured. Trigger asks Masamune if they wants anything to eat but the dog is asleep. Trigger leaps into the water and vanishes under the surface.
He comes back up with his throat slit by Masamune, who orders his family to be killed as well until Matheus says he had no family due to being a pet.