Byakkomaru

Byakkomaru 「白虎丸, lit. White Tiger」 is a high-ranked manifestation-type demon of the Black Demon Series. It formed a contract with Shinya Hīragi and became his Cursed Gear.

Appearance
Byakkomaru's weapon takes on the form of a black, sniping rifle with a bayonet attached at the end. It can either fire off a rapid succession of bullets or fire a single bullet to manifest Byakkomaru.

Byakkomaru manifests as a gigantic white tiger, surrounded by bright blue flames. The tiger can split into multiple tigers in manifestation form to strike down its targets.
 * In the anime, the bayonet has been shown pointed downward to help support the rifle while Shinya is sniping.

Personality
Byakkomaru seems to be very protective over Shinya, as he warned Mahiru to keep away from him, and grew agitated when the latter threatened to kill Shinya if he finds out what she's plotting.

However, he does not seem to care about other matters, shown when he told Mahiru that he doesn't really care who she is and what she is, as long as she doesn't harm Shinya.

History
Unknown, but at some point he got sealed inside a Cursed Gear, and later in the year 2012, became Shinya Hīragi's gear.

Book 6 (Unofficial fan translation)
Byakkomaru was contracted with Shinya. According to the light novel, Shinya underwent an operation to increase his chances of handling a Black Demon Series Weapon, and he emerged from the operation successfully. Ever since then, Byakkomaru became his primary weapon.

Story: Vampire Reign
Shinya uses Byakkomaru in battle against the vampires.

Osaka Arc
In Chapter 54, he manifests to confront Mahiru Hīragi on the roof of a moving car. He demands to know what Mahiru is as he says that she is not a demon, and threatens her if she tries to harm Shinya. He reappears again in Chapter 56 to warn Shinya that Guren is trying to kill him; and when Shinya is getting ready to fight Guren, Byakkomaru is confident in Shinya's chances of winning due to the advantage of distance, but is told to not always expect things to go as planned.

Forms and Abilities

 * Demon's Thrall: Byakkomaru can enter it host's dreams and memories to create nightmares and break it's host's will. This is done in order to take over his body. This ability can only be used against his host.
 * Basic Form: Byakkomaru takes the form of a rifle. Byakkomaru's specialty is long-range firing, and it is not very effective in close-range combat.
 * Multiple White Tigers: Shinya can fire bullets which splits and then manifests into several tigers. Each tiger can strike its target independently.
 * Hidden Bullet: Shinya can fire a bullet which appears behind his target, as shown when fighting with Yūichirō Hyakuya in chapter 17, "Cursed Guinea Pig." It is shown to be an effective surprise attack, but Shinya revealed to Yu that he can only activate that ability once for an unspecified amount of time.

Trivia

 * In the fanbook, it is revealed that the tigers are fired from the rifle. Shinya fires a single bullet, which then manifests into Byakkomaru's tiger form.

Quotes: Vampire Reign

 * "What are you? You are no demon."--To Mahiru Hiragi, Chapter 54, "Sinner's Christmas"
 * "But if you even think of harming Shinya--"--To Mahiru Hiragi, Chapter 54, "Sinner's Christmas"
 * "Shinya. You must not trust him anymore. He will kill you."--To Shinya Hiragi, Chapter 56, "Loose-Lipped Vampire"