Race: Human, Contractor
Messier Code: BK-201
Ability: Electrical Manipulation
Birthplace: China
Former Affiliation: The Syndicate, EPR, CIA
Team (Chronologically): Pai, Amber, Havoc -- Yin, Huang, Mao -- July, Suou Pavlichenko

Throughout the series, Hei is required to bear many names and identities due to the life he leads. It is unknown whether Hei was originally a codename or his real name, however it is used frequently throughout the series to refer to him personally. "Hei" translates to "Black" in Chinese.

In public view, he goes by the name Li Shengshun, masquerading as a foreign exchange student from China staying at the Umitsuki apartment block, Li is known for being polite and well mannered, while also carefully distant; he is also known for having a notoriously huge appetite. As a part of his covert missions for the underground organisation known as the Syndicate, Hei takes on various part-time jobs that allow him to track to his targets.

Infamously known as "the Black Reaper" in the underground, or by his Messier Code "BK-201" by the authorities, Hei is both a highly skilled assassin and infiltrator, alongside being a Contractor with the ability to emit electricity throughout his entire body. In combat, Hei requires either direct contact or a conductive medium (i.e. metal, water, etc.) to affect his opponents; he is also able to control the voltage emitted, allowing him to stun or kill a target as needed. During missions, he typically dons a distinctive white mask and dark bullet-proof coat, alongside equipment attached to his belt which allows him to project wires to either facilitate a kill or to grapple with his surroundings for a greater range of movement (i.e. swinging, abseiling, etc).