Xiao Si

Biodata

Feature	Details
Name	Xiao Si (小四)
Alias(es)	Soul-Devouring Tree; Fourth Master
Species/Race	Reincarnated Soul-Devouring Tree
Affiliation	Bai Muye; bound companion and later his servant
Occupation/Role	Soul devourer, scout, energy supplier, and cultivation support
Status	Active
First Appearance	Chapter 3

Power Progression

Stage / Realm / Level	Chapter	Notes
Reincarnated Seed	3	Returned to its seed state after reincarnation, having lost the worldly wisdom accumulated over endless ages. It could already separate memories and devour souls.
Five-rootlet seed	28	Developed five nearly transparent rootlets after consuming Domain Lord and World Lord souls; could devour only souls below the Immortal level in this state.
Expanded root range	35	Roots reached one-tenth of a light-second, allowing it to devour souls within that distance.
Long-range scanner	53	After devouring five ninth-rank World Lords, its scanning range expanded to twenty light-seconds.
Sapling	55	Sprouted into a little sapling over ten meters tall within Bai Muye's Internal World.
Materialized tree	58 59	Grew beyond one hundred kilometers tall and became able to alternate between reality and illusion, enabling interaction with physical objects.
Matured root network	64	Tree body exceeded one thousand kilometers; roots extended beyond three hundred light-seconds, over one hundred million kilometers.
Billion-kilometer detection	94	Detection range reached roughly one billion kilometers after feeding in the Blue Forest Plain.
Rapid energy-fed growth	124	Absorbed accumulated energy from the Star Tower, growing by at least one hundred thousand kilometers per second as its intake accelerated.
Freed from Internal World confinement	162	Reached a height of one trillion kilometers. The Universal Origin treated it as an extension of Bai Muye, allowing it to leave the Internal World and maintain sub-bodies elsewhere.
Time-control capability	163	Could slow time within a small area by up to one thousandfold after absorbing massive eight-element law divine power.
Space-lockdown teleportation	237	Enabled Bai Muye to escape a Primal Star siege through long-range teleportation despite Space Lockdown.

Background / History

Xiao Si is a Soul-Devouring Tree that reincarnated into a seed and became bound to Bai Muye. It retained knowledge of its former stature but lost the wisdom it had accumulated over endless ages, leaving it with an immature, prideful temperament. Bai Muye nicknamed it “Xiao Si” because the sounds of “soul” and “four” are similar; Xiao Si openly dislikes the name and insists on being called the great Soul-Devouring Tree. 3

While still a seed, it resided first in Bai Muye’s consciousness and later within his Singularity and Internal World. Its growth depends on devouring souls and refining suitable energy, making the Outer Battlefield an unusually favorable environment for both Xiao Si and Bai Muye’s cultivation. 15 46

By Bai Muye’s Immortal breakthrough, Xiao Si had grown large enough for the Universal Origin to recognize it as an extension of him. It could then remain outside the Internal World and leave sub-bodies in Bai Muye’s God Kingdom to replenish divine power for his clone. 162

Appearance

Xiao Si began as a pitch-black seed with faint multicolored brilliance visible across its surface. As it grew, it became an enormous black tree with a thick trunk, dense upper branches, and a cloudlike canopy. 15 58

• Its seed form produced nearly transparent rootlets. 28
• Its mature tree body remained deep black despite its dense foliage. 58
• At over one hundred kilometers tall, its trunk was nearly ten kilometers in diameter. 58
• By Bai Muye’s Immortal breakthrough, its height had reached one trillion kilometers. 162
• It can shift between tangible and illusory states. 59

Personality

Xiao Si is childish, haughty, and intensely proud of its identity and former power. It regularly boasts of what it will be capable of “when it grows up,” takes offense at being underestimated, and adopts the self-important title “Fourth Master.” 3 15 64

It is also excitable about opportunities to devour souls and energy, sometimes complaining when potential battles end without enough deaths for it to feed on. 51 58 Despite this greed, it consistently supports Bai Muye’s survival and cultivation, including preserving resources it was naturally drawn to consume and spending its own rare origin material to heal him. 34 64

Abilities & Skills

Soul Devouring and Memory Processing

Xiao Si devours the souls of fallen beings, separates useful memories, and refines harvested energy for Bai Muye.

• It can separate combat-related memories from emotional and personal content before Bai Muye integrates them. 3
• It provides Bai Muye with cultivation insights, combat experience, and purified memories from devoured souls. 10 94
• In its seed stage, it can devour only souls below the Immortal level. 28
• A soul must be consumed quickly after death before it dissipates. 28
• It can refine devoured energy into pure energy or Origin Energy for Bai Muye’s cultivation. 32 47

Scouting and Detection

Xiao Si’s root system functions as Bai Muye’s primary detection network.

• Its roots can detect threats and warn Bai Muye before an ambush occurs. 15 153
• It can detect targets and hidden locations beyond the reach of ordinary detection equipment, including the Spirit Slip Race Holy Temple and the Mi Ya Clan Ancestral Land. 59 108
• It can perceive Soul Entities and assess their approximate strength within the Black Soul Stone Forest. 213
• Its detection can bypass concealment functions that would obstruct ordinary detectors. 58

Defensive Support and Recovery

Xiao Si protects Bai Muye’s critical weak points and sustains his long-term combat capability.

• While residing in Bai Muye’s Singularity, it can prevent the Singularity from being destroyed. 4
• It used its rare Spirit Marrow Fat to heal Bai Muye’s severe internal injuries, torn flesh, and broken bones during his battle with the Tiger Armor Zerg. 34
• It can conceal portions of Bai Muye’s Internal World and genetic potential from powerful observers. 133
• Its God Kingdom sub-bodies can continuously replenish the divine power expended by Bai Muye’s clone. 162 163

Spatial Movement and Teleportation

As its roots developed, Xiao Si gained increasingly powerful spatial utility.

• It can materialize, become illusory, and interact directly with physical objects such as a palace core. 59 60
• Its roots can entangle targets and drag Bai Muye’s spaceship into hidden locations. 109
• It can teleport objects and divine-power fragments to locations reached by its roots. 55
• It helped Bai Muye evade Venerable Mingsheng and later enabled escape through Space Lockdown. 146 237

Time Manipulation and Secret-Pattern Support

After absorbing vast quantities of divine power, Xiao Si developed support abilities beyond feeding and scouting.

• It can manifest complete Secret Pattern Diagrams for Bai Muye’s study. 163
• It can slow time in a small area by up to one thousand times. 163
• It identified a vast Secret Pattern Diagram formed by the combined trajectories of all 10,081 Primal Stars. 237

Limitations

• Xiao Si cannot actively attack or kill living beings; Bai Muye must defeat enemies before it can consume their souls or energy. 15 55
• Its energy absorption is selective and requires sufficiently pure energy, limiting its growth rate in some environments. 46 124
• It could detect Yuanzu’s suppression within the Universal Origin but lacked the strength to rescue him. 153
• Although it can absorb ambient soul power, it considers ordinary ownerless soul power inefficient and of limited value. 213

Relationships

• Bai Muye — Bound companion, cultivation partner, and later servant. Xiao Si supplies memories, energy, scouting, healing, and escape methods, while Bai Muye provides souls and energy for its growth. 15 46 162
• Xiao Wu — Fellow assistant within Bai Muye’s Internal World. Xiao Wu eventually addresses Xiao Si as “Fourth Master” and works with it to navigate battle-heavy regions. 70 87
• Molly — Xiao Si produced a Heart-Linking Fruit used to facilitate her temporary soul fusion with Bai Muye. 111
• Yuanzu — Xiao Si established protected contact between Bai Muye and the suppressed True God through one of its roots. 153

Story Role / Major Arcs

• Life-and-death battles — Separates and purifies the memories of Bai Muye’s defeated opponents, accelerating his combat and cultivation development. 3 10
• Outer Battlefield growth — Feeds on fallen Domain Lords and World Lords, expands its root network, and provides Bai Muye with refined energy for body-refining cultivation. 28 46 47
• Dragon Mountain Pool and Yanxin Palace — Detects the Holy Temple, helps Bai Muye enter it, and later assists in retrieving its core. 59 60
• Miya Continent — Detects the hidden Mi Ya Clan Ancestral Land and uses its roots to draw Bai Muye’s spaceship into it. 108 109
• Immortal era — Gains the ability to leave Bai Muye’s Internal World, sustain his clone’s divine power, manipulate local time flow, and provide high-level teleportation. 162 163 237

Notable Quotes

“I told you not to call me Xiao Si. I am the great Soul-Devouring Tree...” 3

“When I grow into a sapling in the future, you'll know how powerful I am...” 15

Trivia

• Bai Muye named Xiao Si because the pronunciations of “soul” and “four” sound similar. 3
• Xiao Si repeatedly refers to itself as “Fourth Master.” 64 87
• It claims that, at its peak, even a Hunyuan Progenitor could do nothing to it. 3