He's a renegade foot soldier from the sky fortress that invaded thirteen years back—one of the Dusters with shape-shifting and regenerative powers who broke ranks with the rest of his unit. Him and his crew made a pact to take down the Dragon Keepers from the inside, which meant going deep undercover in their organization.
For most of the series, he operates under two main identities. One's just a regular black-haired teenager—forgettable enough to blend in. The other is as Hibiki, a stolen identity he uses to navigate Dragon Keeper circles and get closer to their inner workings. The dual cover lets him play both sides without raising suspicion, at least for a while.
Content compiled by AnimeList.moe from publicly available sources.
