Hei

Hei is the main protagonist of the Darker than Black anime.

Hei also known as the Black Reaper or BK-201, is a human who gained Contractor powers. He has worked with various organizations including the Syndicate and CIA. He is the older brother of Bai.

Appearance
Hei is a young man of slender build with black hair and dark blue eyes. When in his Li Shengshun persona, he wears the casual attire of an exchange student. When operating as a Contractor, Hei dons a bullet-proof trench coat and a white pierrot-inspired mask that fully conceals his face.

After the events that transpire at Hell's Gate, Hei lets his hair grow out and neglects shaving. His trenchcoat has become worn and he mostly wears a ski jacket.

Shortly after learning that Yin is still alive and in danger, Hei cuts his hair back to normal length, shaves, and returns to his "Black Reaper" attire.

Personality
As a member of the Syndicate, Hei regularly takes on false identities and personas for his missions and day to day life, such as Li Shengshun: a good-natured, timid Chinese exchange student who tries to help others but otherwise generally keeps to himself.

Hei is a calculating assassin. Unusually for a Contractor, Hei exhibits and sometimes acts upon emotions. Hei also has a huge appetite, often surprising people with the amount he can eat. Despite having the power of a Contractor, Hei still has his human emotions. He deeply cares for his sister, Bai, and searches for her after her disappearance.

After Yin's disappearance, a drastic change came upon Hei's personality. He takes up drinking, becomes more ruthless, gets angry easily and would often lash out at Suou, slapping her across the face whenever she said something that angered him. He rarely showed such behavior prior to this, but after learning of Yin's whereabouts, Hei reverts back to his previous attitude showing his care for Yin, while also developing feelings of care toward Suou.

Abilities
Peak Human Condition: Hei's contract powers are especially useful because of his amazing agility, speed, endurance, dexterity, and natural strength.

Expert Hand-to-Hand Combatant: Hei is obviously extremely skilled in martial arts and is an accomplished acrobat easily able to do backflips and mid-air cartwheels with little effort in terms of physical strain. Hei's natural abilities are so impressive that even without his contractor powers Hei is easily able to take on other contractors.

Tactician: Not unlike many Contractors, Hei possesses a very pragmatic and resourceful intellect; demonstrating a knack for improvisation during the heat of combat. Since Hei's contractor ability can only kill once in direct contact with the intended target, Hei often relies on taking his opponents by surprise in order to gain the advantage (as evidenced by his gambit during his first fight with Wei). His tactical unpredictability and resourcefulness coupled with his almost bullet-time speed makes him a daring foe.

Contractor Power
Molecular/Electricity Manipulation: Hei possesses the ability to generate and discharge electricity through conductive media (i.e. he cannot discharge it through air or concrete) at sufficiently high amounts to kill grown men or short out a building's electrical systems. The power is more than simple electric shocks, as he can alter matter on the quantum level. He has shown the ability to transform integral particles on the quantum level. He is capable of special particle luminance, meaning he is able to change molecules similar to how humans are changed into contractors. This ability is also one of the most, if not the most, powerful and coveted powers known as it is the only one capable of altering gate particles at will. This ability is not actually his as he is really only human, but it was granted to him when his sister fused with him. While in possession of the Meteor Fragment, Hei's powers were amplified to the extent that he was able to destroy a large portion of South America almost effortlessly.
 * Obeisance: None. This inheritance means that, unlike other contractors, Hei doesn't have an Obeisance. The reason behind this is that he is actually a human who has fused with his sister, a Contractor, therefore he has no price to pay.

Equipment

 * Mask: Hei wears a white mask with a purple lightning symbol over the right eye. It also has a thin red slit across the mouth.


 * Knife: His trademark weapon is a knife on a metal wire, which he uses as an offensive weapon, a grappling hook, or as a conduit through which to discharge his electricity.


 * Wire: In addition to using it with his knife, Hei also uses his wire with a carabiner attached to the end, which allows the wire to anchor to any object that it wraps around. This is also used to wrap around enemies necks and allows Hei to deliver lethal shocks.


 * Black Trench Coat: Hei's long black trench coat is bullet proof (often used as a shield), and works only with his powers.


 * Crossbow: To aid in infiltrating a building, Hei has made use of a collapsible crossbow to fire a rope large distances. He keeps the crossbow in a satchel.


 * Lie Detector Sticker: Hei wears a transparent sticker on the back of his neck to pass a lie detector test and conceal his identity as a Contractor while inside PANDORA.

Trivia

 * Hei's original Messier Code was going to be 201-BL. 201 was chosen because it was the number of Tensai Okumura's apartment at the time. "BL" was from "Black" but was rejected due to certain implications it might have.
 * The number 201 appears frequently throughout the series.
 * Hei's apartment room number is 201, as in BK-201
 * In the first season, second opening, 0201 can be seen in the pane of glass Hei walks past.
 * In episode 11, 201 can be seen twice on Hei's passport, once under his picture (No018-00201) and again under his nationality (AR201).
 * In episode 19, Hei is asked to read the page 201 from the Black Book.
 * In episode 2 of Darker Than Black: Gemini of the Meteor, the number 201 can be seen in Suou's camera as she's taking photographs of her brother walking for the first time.
 * His code name "Hei" means "black" in Chinese.