Viz Edition Release Date: April 14, 2009
Haine, the “Stray Dog”: a cipher of a young man with a mysterious metal collar bolted to his neck and a disturbing talent for mayhem. Badou: a hired gun for petty jobs legal and non, whose reckless façade hides a serious intent. Naoto: a preternaturally skilled swordswoman searching for the assassin who cut down her family and mentor. Mihai: a middle-aged former hitman, trying live a quiet life but haunted by the deaths of his lover and protégé. Driven by their ghosts—both dead and alive—and a desire for truth, all are inexorably drawn to the “Underground,” the dark and dangerous sector below the city that holds all the secrets—but secrets that can only be had for a price.
Mihai reflects on his life as he prepares to open up a bar (coffee shop?). Ten years ago, he trained a young boy named Ian to become a gunman. However, the boy killed the woman he loved and he never figured out why. After it's revealed that the boy has become a new Mafia boss, Mihai decides to face him near her grave. A sniper prepares to take them both out, but Ian sacrifices himself as they both shoot the third attacker. With his dying breath, Ian tells Mihai that he killed the woman because he thought of Mihai as a real father rather than the former Mafia boss. As a boy, he grew jealous of the affection he showed towards her, and he wanted Mihai's love for himself, so he took the initiative and killed her.
Badou is spying on a couple having sex in the daytime, working on a "marital infidelity" case while hanging outside their window. Suddenly, he spots a cat named Julian and tries to grab it for the large reward a rich family has offered for its safe return. However, the cat moves away before he can grab it and sends him falling down before the rope holding him goes taut. As he straightens himself out, he finds himself facing the mafia don of the West side in a rather compromising position and snaps a picture. The don sends goons to chase after him, and Badou takes refuge in Mihai's bar.
Mihai's friend suggests that he should sell the photos and embarrass the don, but Badou's afraid that the don's thugs will hunt him down anyway, and asks Mihai for help. Mihai asks for money to help him, and Badou can only come up with pocket change. Suddenly, the don's goons strike at the bar. Badou tries to take a long-awaited cigarette break, only to have the last one in the room destroyed by a bullet, causing his psyche to snap. Badou quietly walks outside and pretends to surrender, then guns down all of the don's goons with a pair of SMGs.
Afterwards, he decides to sell the photo for money and embarrass the don anyway. However, Mihai and his friends make him clean up the damage the gunfight has caused to the bar.
A young girl sees her parents get murdered in front of her by someone with a sword strong enough to cut three people, leaving an X-shaped scar across her torso. A man soon walks up to her bloodied body and asks if she wants to live. The man takes her home and heals her, but because she doesn't seem to have a name the man decides to name her Naoto, after some other person he remembers. Naoto appears to accept the name, but also harbors a deep grudge against this man because she believes he killed her parents.
The man decides to teach her with real blades and fighting, not holding back even as the girl tries to find a way to kill him. However, her revenge is stolen when the man's other student, Nagato, kills him in a duel beforehand. Naoto gets into a fight with Nagato, and rends him through the side of his stomach. Nagato tells Naoto that the man was hiding the fact that he didn't kill her parents, but another one of his former students who was also named Naoto did it. As Nagato stumbles away with his large wound, Naoto wonders if her teacher did it on purpose to make her fight harder against him, but because he was killed now she will never know.
A young man named Haine walks around the Underground when he sees a little girl being abused by a group of men. When he sees the girl has real wings sticking out of her back, he decides to save her. Apparently, the two of them share the fact that they are genetically modified people, though he doesn't specify what his own modification was.
Suddenly, the girl's pimp decides to get the girl back, shooting Haine in the stomach with a shotgun and kicking him out a window before dragging her back to his home. Haine strangely recovers from the damage until he appears completely healed. After Badou tells him the girl's whereabouts, he decides to go on a mission with Badou to get the angel-girl back, visiting a nearby church to grab a couple guns and ammo from his stash there. The blind priest frowns at his church being used to hide the guns, but lets him go anyway.
Haine crushes all of Badou's cigarettes to trigger his nicotine-starved crazyness, which causes a helpful distraction while he goes to rescue the angel girl. The pimp shoots Haine in the chest and neck, but Haine shrugs the bullets off and shoots the pimp in the head, revealing his metal collar and telling the pimp he should have aimed for the head. Having saved the girl, he decides to let the blind priest hide her, though the priest appears to be a bit of a lolicon and Haine wonders if he truly is blind.
Back in the streets of the Underground, Haine runs into a man who warns him that someone named Giovanni is coming for him.