Are you some kind of assassin or something?

The main character of this story. While on a trip to the United States, he happens to witness a murder and tries to flee, but is taken captive.
Recognizing the instinctive skill he displays in his attempt to escape, his captors wipe his memory and force him to train as an assassin.
Under the instruction of Ein—Phantom—his latent abilities awaken, and he is reborn as the assassin known as Zwei.

I was born to kill.

Inferno's top sniper—the girl known as Phantom.
She is a killer shaped through Scythe Master's brainwashing. Stripped of all memories of her former life, including her name and age, she was trained to become an expert in assassination and espionage, suppressing all emotion to carry out her missions.
She also possesses extensive specialized knowledge and is fluent in English, Japanese, German, Russian, and Cantonese. By order of the organization, she takes on the task of training the protagonist as an assassin. But by taking him on, she may be in for much more than she bargained for...

You should know better than to ask a woman “why.”

A high-ranking executive of the criminal organization Inferno. Despite her youth, she is a shrewd woman who has managed to claw her way to the upper echelons. Calm, collected, and calculating, she is always one step ahead of her opponents.
She is also ruthlessly ambitious, and will stop at nothing to achieve her goals, no matter how big the risk.
She sympathizes with the protagonist as a captive of the organization, and bestows various favors upon him. However, her position is threatened by her subordinate, Scythe Master. As the protagonist is being groomed as Scythe's second pawn, she schemes to steal him away. But in doing so, she begins to develop feelings for him that go beyond what she intended...

I can help.

A girl the protagonist meets after he has become a professional killer. After running away from home, she was taken in by a prostitute and has lived in the inner city ever since.
After a slip-up by the protagonist, she becomes entangled in the organization's schemes, and her life is put at risk.
With no other choice, he takes her in under the pretense of making her his apprentice to keep her safe, but in the process, she grows fond of him. As the two are practically forced to live together, she opens her broken heart to him.
However, she is completely unaware of the cruel fate that awaits her...

But right now, in this moment, I have the power to help you.

A girl attending a Catholic school in Japan. She's the same age as the protagonist, who has recently transferred in. Drawn to his mysterious allure, she begins to develop feelings for him.
She often lets herself be carried away due to her easygoing nature, but when push comes to shove, she reveals a sharp mind and a strong inner resolve.
Her origins conceal a secret even she does not know—one that will drag her from her peaceful life into a world of violence...

I’ll take you on then. Let’s fight.

A skilled hitwoman for the organization Inferno.
She harbors animosity toward Ein and the protagonist as she aims for the top spot.

Excellent, Ein! Wonderful!
You truly are the best material I’ve ever had.

Claudia's subordinate. An expert in brainwashing and reeducation who trained Ein.
Though a relative newcomer to Inferno, his ability to cultivate exceptional assassins has earned him recognition, and he continues to rise through the ranks at an astonishing pace. He is overwhelmingly confident, and wantonly puts his desires and ambitions on display for all to see.
He seeks to overthrow his superior, Claudia, and take her place in the organization. This is the very man who recognized the protagonist's potential and brought him into this world.

...You better not die on me, kid!

A markswoman for the organization, as well as Claudia's subordinate and dearest friend.
She can be quite crass, but harbors a strong sense of loyalty and honor. She has no interest in personal gain and remains uninvolved in the organization's schemes.
She always speaks her mind and lives her life without a care. For that very reason, she will openly display her contempt for self-minded schemers.

Let the Phantom name strike dread into the heart of the underworld.

The leader of Inferno.
Formerly a member of a Colombian drug cartel.
Born into a family of leading figures in the underworld, he was born into excessive wealth and power in a nation ravaged by poverty.
He is a modern-day aristocrat, accustomed to ruling over others. His dignity and refinement befit nobility, while his ruthlessness rivals that of any despot. Those who defy him are swiftly granted the freedom of death.

And that’s God’s truth, cross my heart.

An executive of Inferno.
Boss of the most powerful street gang in Los Angeles, the Bloodies.
He is one of the founding members of the organization and the face of its operations in LA. He is effectively the second-in-command.
He's close enough with McGuire to call him "Ray." He has been suspicious of Claudia ever since a certain incident in the past.