Xu Xi

Biodata

Feature	Details
Name	Xu Xi (徐夕)
Alias(es)	Black Mask 42 48
Species/Race	Human; a former Unit 701 enhanced operative 47 61
Gender	Male
Affiliation	Unit 701 (former); Po On Road Public Library (former) 46 47
Occupation/Role	Librarian; former Unit 701 training instructor; masked vigilante 7 47 48
First Appearance	Chapter 7: “Getting Acquainted”

Background / History

Xu Xi worked at the Po On Road Public Library, where he first met Yang Chu. Though he appeared shy and mild-mannered, he was widely read, perceptive, and notably skilled at Chinese chess. He and Yang Chu gradually became friends through shared meals, reading, and chess games. 7 16 38

Before coming to Hong Kong, Xu Xi served as a training instructor for Unit 701, a former Soviet human-enhancement unit. The organization modified its personnel to eliminate pain sensation, creating operatives with unusually developed physical potential. Xu Xi eventually escaped Unit 701 rather than remain a tool of its captain, Xiong Ju, whom he considered an ambitious terrorist threat. 47 97

For years, Xu Xi operated secretly as Black Mask, targeting criminals in Hong Kong. Newspaper reports had used the name “Black Mask” since at least the period following the demolition of Kowloon Walled City; it was not a name Xu Xi chose for himself. 48

After Unit 701 resurfaced in Hong Kong, Xu Xi resigned from the library and brought Yang Chu to his concealed base in an abandoned factory. He revealed his past and asked Yang Chu to help destroy Unit 701 before Xiong Ju's plans harmed more civilians. 46 47 48

Appearance

In civilian life, Xu Xi presents himself as a gentle, scholarly man with a shy smile and plain, slightly bulky clothing. His unassuming demeanor causes others to see him as harmless and introverted. 7 16 94

• As Black Mask, he wears black clothing, a black hat, and a black face mask. 58 60
• He drops his habitual shy smile when operating from his underground base or confronting Unit 701. 47
• His masked identity is recognized by criminals and hostages through newspaper reports. 48 92

Personality

Xu Xi is considerate and restrained in ordinary life. He offers Yang Chu food without pressure, avoids prying into his friend's past, and treats people with quiet courtesy. His library colleagues regarded him as good-natured, helpful, and unlikely to compete or scheme against others. 7 45 46

Behind this reserved exterior, Xu Xi is decisive, analytical, and willing to confront danger directly. He resigns without hesitation once Unit 701 becomes a threat, studies the organization’s movements, and repeatedly risks himself to stop Xiong Ju's attacks. 46 48 68

His sense of justice is tempered by an understanding of human complexity. He does not automatically condemn Yang Chu for seeking revenge, but remains concerned that Yang Chu may lose his remaining morality and become a “monster.” 78 95

Abilities & Skills

Pain-Insensitive Enhanced Physiology

Xu Xi underwent Unit 701's human-enhancement program, which obstructed pain transmission and left its subjects unable to feel pain. 47 61

• Unit 701's modifications were derived from research into congenital insensitivity to pain. 47
• The program was intended to remove fear of injury and unlock greater combat capability. 47
• Unit 701 operatives are described as possessing strength and reaction speed beyond ordinary people; Xu Xi is regarded as close to a “perfect warrior.” 97

Combat Training

As Unit 701's former training instructor, Xu Xi trained operatives including Ruolan. 43 47

• Moves rapidly across difficult terrain, including shipping containers and rooftop structures. 60 93
• Uses thrown metal discs as concealed weapons. 93
• Can subdue Xiong Ju in direct combat, though Xiong Ju escaped when an outside force intervened. 73
• Coordinated closely with Yang Chu during the final confrontation with Unit 701. 93

Surveillance and Technical Improvisation

Xu Xi retained a limited portion of Unit 701's advanced technology and adapts it for tracking and communications. 58

• Secretly placed a compact tracker on Yang Chu to locate him across Hong Kong. 58
• Modified a large signal receiver from second-hand equipment to track Xiong Ju's movements. 62
• Carries specialized equipment and “small toys” useful for infiltration and escape. 92
• Uses a paraglider to reach and leave elevated locations, including the Central Building rooftop. 92 94

Equipment

• Black Mask attire — Black clothes, hat, and mask used to conceal his identity. 58 60
• Tracking devices — Compact transmitters and a modified signal-tracking receiver. 58 62
• Thrown metal discs — Concealed weapons used against armed opponents. 93
• Paraglider — Used for rooftop access and escape. 92 93
• Hidden factory base — An underground living and operations space containing laboratory equipment, documents, beds, and tracking devices. 47 62

Relationships

• Yang Chu — Friend and ally. Xu Xi trusts Yang Chu despite knowing he is dangerous, recruits him against Unit 701, and later chooses to help him escape Hong Kong rather than stop his revenge. 47 48 78 92
• Ruolan — Former student from Unit 701. Xu Xi remains protective of her after her injury and helps conceal her identity. 43 47 78
• Chen Guibin — Friend and police officer. Chen worries about Xu Xi's safety and association with Yang Chu, while Xu Xi seeks his help when Unit 701 threatens Kowloon Police Station. 45 62 68
• Xiong Ju — Former captain and adversary. Xu Xi deserted Unit 701 because of Xiong Ju's ambitions and seeks to capture or eliminate him. 47 60
• Unit 701 — Xu Xi's former unit. He views its surviving members as a terrorist force and works to dismantle it. 47 48

Story Role / Major Arcs

• Library friendship — Meets Yang Chu at the Po On Road Public Library, sharing meals, books, and chess while concealing his past. 7 16 38
• Black Mask reveal — Appears in his masked identity at the public pool, revealing a connection to pain-insensitive killers and Unit 701. 42 43
• Unit 701 conflict — Resigns from the library, reveals his former role as Unit 701’s instructor, and forms an alliance with Yang Chu against Xiong Ju. 46 47 48
• Kowloon Police Station crisis — Works with Chen Guibin to prevent Xiong Ju from destroying the police station with planted bombs. 68 73
• Central Building battle — Supports Yang Chu during the rooftop hostage crisis, helps confront Unit 701, and escapes with Yang Chu by paraglider after Xiong Ju's helicopter assault. 92 93
• Departure from Hong Kong — Plans to leave Hong Kong with Ruolan after Unit 701's actions expose them to greater scrutiny. 95