Xiao Si

Biodata

Feature	Details
Name	Xiao Si (小四)
Alias(es)	Meng Po; Qin Xin (suspected) 108 397
Species/Race	Ghost 137
Gender	Female
Affiliation	Wang Ye's group; Underworld
Occupation/Role	Wang Ye's ghost subordinate and scout; former Underworld strategist 45 1051
Status	Deceased; dissipated herself to strengthen humanity's chance against the Heavenly Court 1051
First Appearance	Chapter 45

Power Progression

Stage / Realm / Level	Chapter	Notes
Half-King (true strength, retrospectively assessed)	449	Wang Ye later judges that Xiao Si was originally around Half-King level; after being sealed, she could barely maintain Ghost General strength.
Ghost General (while sealed)	449	Her power was heavily restricted by seals, including the Bronze Nail and later Xiao Wu's Buddhist-style splinter seal.
Ghost King	449	Her strength steadily grows even while inactive; Wang Ye notes that she reaches Ghost King level within months and narrowly loses to him in a direct fight.

Background & History

Xiao Si's earliest known role was as A Nian's silent guardian. She appeared beside the young A Nian during her most helpless period, protected her through dangerous travels, and remained her only family even after A Nian became strong enough to no longer need protection. Xiao Si initially could not speak or explain her origin. 258 259 327

Before A Nian's death, Xiao Si managed to state her name for the first time. A Nian then transferred a white sphere from her brow into Xiao Si, restoring memories and awakening her consciousness. Xiao Si subsequently asked for the Bridge of Helplessness—the location closest to A Nian—and took the name Meng Po. 395 396 397

Later revelations identify Meng Po as a divided aspect of Xiao Si rather than a wholly separate being. To survive the ancient conflict, Xiao Si joined the Heavenly Court, split herself into separate existences, and concealed her consciousness. One thread ultimately remained with the Underworld as Xiao Si, while Meng Po continued pursuing a plan to strengthen the Underworld and undermine the Heavenly Court. 393 398 1049 1051

After the Heavenly Court's girl is defeated, Meng Po absorbs her soul; the two Xiao Si-like souls merge and enter Xiao Si's body. This restores Xiao Si's wisdom and forces her to confront the failure of her long-term plans. 1049

Appearance

Xiao Si is a peerlessly beautiful woman with a slender build, pale skin, and usually vacant, numb eyes. Her stillness and lack of expression often make her resemble a statue or puppet rather than a person. 45 50 211

• Originally had a Bronze Nail embedded in her forehead, later replaced by a blood-stained wooden splinter seal. 45 116 272
• Her ghost aura can create an instinctive sense of rank suppression in other ghost-like beings. 561
• Wore a pink bunny-eared hat to conceal the nail while accompanying Wang Ye. 50
• Received a women's Ghost Messenger uniform marked with red, blood-like accents. 244
• Her appearance can be deceptive: Wang Ye describes her as a harmless-looking “vase,” despite her ability to fight while carrying severed heads. 559

Personality

For much of her time with Wang Ye, Xiao Si appears emotionally numb, silent, and mechanically obedient. She follows simple instructions with excessive literalness—for example, when ordered not to let Su Wenqian speak, she specifically struck his mouth. 45

Her passivity conceals independent thought. She secretly leaves Wang Ye's home at night, imitates his posture and movements, resists some commands, and later learns to write modern simplified Chinese so that she can communicate. 50 92 191 271 272

Xiao Si is protective toward A Nian, remaining beside her despite being increasingly unnecessary in combat. After regaining her wisdom, she becomes introspective and openly acknowledges her fear of death, selfishness, and regret over having treated survival as her sole purpose. 327 1049 1051

Abilities & Skills

Ghost Physiology

Xiao Si possesses a powerful ghost body strengthened by long-term ghost aura.

• Can continue acting after severe impacts and physical damage. 68 281
• Her body can absorb or nullify certain supernatural energies, including the energy from spirit tablets and a ghost-rule altar. 108 119
• Her durability is not absolute; the Fengdu City plaque burns her hands and draws blood when she tries to move it. 281
• Her blood can strengthen Yang Chen's ghost aura. 561

Stealth and Assassination

Xiao Si's greatest combat advantage is her unpredictable movement speed.

• Can silently appear behind targets without being noticed. 271 449
• Participates in coordinated ambushes with Wang Ye and Xiao Wu. 301 304
• Favors decapitation and head-taking attacks, though Wang Ye repeatedly criticizes this habit. 301
• Can swiftly attack vital organs with sharpened nails, including tearing out an Old Monk's heart. 304

Physical Combat

Xiao Si is capable of confronting powerful opponents directly.

• Severely injures Su Wenqian after Wang Ye gives the order. 45 46
• Matches a golden-armored youth's spear strike head-on with her bone-cutting knife. 449
• Xiao Wu, despite his own overwhelming strength, judges himself inferior to Xiao Si's unsealed power. 115

Seals, Control, and Resistance

Xiao Si has repeatedly been sealed, but no method completely guarantees control.

• A Bronze Nail initially suppresses her, though smashing it with Wang Ye's wooden chair can briefly restore her consciousness. 102 116
• Paper Money suppresses her energy fluctuations and makes her movements easier for Wang Ye to command. 102
• Xiao Wu reinforces her seal with a splinter that becomes a swastika-shaped mark, forcing out the Bronze Nail. 116
• Wang Ye later discovers that his control is weakening and suspects that he may never have truly controlled her. 92
• Xiao Er can directly force Xiao Si to act even when Wang Ye cannot. 227

Learning and Communication

Though initially unable or unwilling to speak, Xiao Si demonstrates observation and learning ability.

• Imitates Wang Ye's lounging posture and movements after watching him. 50
• Writes “Yellow Springs” after Wang Ye reveals that he entered a coffin in Qin Manor. 271
• Writes that she does not know her purpose, but feels comfortable around Wang Ye. 272
• Gains clearer self-awareness, including an understanding of privacy and gender separation. 244
• Eventually regains speech and identifies herself as Xiao Si. 395 397

Soul Division and Restoration

Xiao Si's existence is tied to Meng Po and the Heavenly Court's girl through divided souls.

• Meng Po describes herself as a stray soul split from Xiao Si. 393
• Meng Po and the Heavenly Court girl each release a soul with Xiao Si's appearance; the souls merge and enter Xiao Si. 1049
• The merger restores Xiao Si's wisdom and memories, allowing her to understand the consequences of her past actions. 1049

Equipment / Weapons / Items

• Bone-cutting knife — Associated with Xiao Si from the earliest investigations and wielded by her against the golden-armored youth. 220 449
• Bronze Nail — Her original restraint; removed when Xiao Wu reinforces her seal. 102 116
• Wooden splinter — A seal removed from her own head; its blood-stained state may enhance its sealing properties. 116 272
• Paper Money / spirit money — Used by Wang Ye to suppress her energy and regain smoother control over her movements. 102 132
• Ghost Messenger uniform — A fitted women's uniform issued by the Heavenly Group. 244

Relationships

• Wang Ye — Her handler, companion, and frequent source of suspicion. He initially treats her as a controllable weapon, but continues keeping her despite her instability and later learns that she feels comfortable around him. 45 132 272
• A Nian — Her ancient companion and family. Xiao Si protects A Nian through her weakest years, while A Nian's final act restores Xiao Si's consciousness. 327 395 396
• Meng Po — A divided aspect of Xiao Si connected to the Underworld; the two are later reunited through merged souls. 393 398 1049
• Xiao Wu — An ally whose memories contain an image of Xiao Si. He considers her stronger than himself, but is able to reinforce her seal. 115 116 219
• Xiao Er — Can directly control Xiao Si's body, a capability that surprises Wang Ye. 227
• Lu Qing — Believed by Wang Ye to have deliberately guided Xiao Si to his side, though Xiao Si's true connection to him remains unresolved. 586

Story Role / Major Arcs

• Wang Ye's early ghost subordinate — Introduced as Wang Ye's “friend,” Xiao Si is used as his enforcer against Su Wenqian and later aids him in supernatural investigations. 45 64 68
• Unstable sealed weapon — Her nighttime movements, resistance to commands, and potentially overwhelming unsealed power make Wang Ye increasingly distrustful of her. 50 92 115 137
• Ancient-domain companion — Xiao Si accompanies Wang Ye through the ancient domain, where the name Qin Xin appears and supernatural rules repeatedly fail against her. 108 119
• A Nian's guardian in the Three Pages of Paper — Wang Ye witnesses Xiao Si's ancient bond with A Nian and learns that she was not merely a mindless ghost servant. 258 327 395
• Ghost Messenger squad member — She joins Wang Ye, Xiao Wu, and Xiao Er as part of the Ghost Messenger group, acting as a stealth fighter and scout. 224 244 304
• Underworld revelation and final sacrifice — Following the reunion of her divided souls, Xiao Si accepts that she cannot escape fate. She fights for the Underworld and ultimately dissipates herself to give the Human Race a chance against the Heavenly Court. 1049 1050 1051

Notable Quotes

“My name is... Xiao Si.” 395

“But, from today onwards... call me Meng Po.” 397

“I don't know, but I'm very comfortable with you.” 272

“Do you really only ever see me as... a tool?” 1051