Butler Yu

Butler Yu, whose full name is Yu Elvedaro, is the fish-scaled demon administrator who becomes one of Aengus Degaro's earliest local retainers in the Demon World. His service grows from cautious hope and Darkness Haki-enforced loyalty into practical stewardship of troops, supplies, and conquered populations. He remains with the Liberation cause long enough to be remembered as a legendary loyalist and to receive a personal blessing after Aengus's return. (Chapters 87–127, 340, 412, and 439)

Biography

Black Swamp to Preparation For Leaving

Yu enters Aengus's household as the Dark Valley Barony's personal butler, seeing the new half-demon lord as a possible source of hope while also fearing his power. Aengus reinforces that allegiance with Darkness Haki and relies on Yu for discreet exchanges of demon cores, mustering soldiers, and explaining local identities. Yu chooses hardworking subordinates for enhancement, accepts fusion with defeated beasts, joins field operations, and later administers ranks, posts, treasury supplies, and core distribution, turning personal attendance into the infrastructure of a growing army. (Chapters 87–127)

Synthesize: New Race to Attack On Crimson City

When Aengus returns in a newly transformed state, Yu recognizes his true lord and resumes a place among the senior demon entourage. He travels with Bella Bellfrost, Aria, Sen, Sienna, and other commanders from Belial's estate toward Crimson City, riding the evolved hydra Gabi. The chapters do not give Yu an independent strategic decision in this campaign, but his continued inclusion shows that administrative loyalty has earned him a stable position close to the imperial family and its military leadership. (Chapters 265–273)

Grand Unification

During the Grand Unification gathering, Yu helps the human and demon commanders contain mutual hostility when the two populations first assemble under a common sovereign. The scale makes control nearly impossible until Aengus intervenes, so Yu's role is supportive rather than decisive. Later accounts place him among the heroes who keep Mythraldor from bowing to war or time, and Aengus grants him a gift after returning, confirming continued service without specifying the blessing's exact nature. (Chapters 340, 412, and 439)

Appearance and personality

Yu is a humanoid demon covered in subtly shimmering fish-like scales. He is less physically imposing than many demons around him, but Aengus notices a sharp mind, dedication, and hope behind his deferential manner. Yu speaks respectfully, bows with a hand over his chest, obeys unusual orders without demanding explanations, and knows when to withdraw from private situations. His courage is practical rather than boastful: he worries about superior enemies, volunteers support, and advances when commanded. (Chapters 87, 91–97, and 106)

Skills, laws, and abilities

Yu begins below Aengus's Greater Demon forces but is selected for synthesis because of reliability and intelligence. Aengus merges him with defeated creatures, after which Yu is counted among sixteen Greater Demons advancing in formation; later Aengus grants him a System as part of the first empowered hierarchy. The source does not show Yu's status panel, fusion components, System abilities, element, or named personal attack, so his exact mechanics and combat ceiling remain unresolved. (Chapters 93, 97–99, and 118)

His clearest demonstrated strengths are command support and administration. Yu handles discreet market transactions, assembles the barony's soldiers, selects suitable personnel, assigns new subjects according to strengths and weaknesses, tracks millions of demon cores, and reports completed distributions. He also deploys with elite warriors in battle, but no scene isolates his strikes from the surrounding army. The later description of “unfathomable skill and loyalty” is retrospective praise, not a measurable rank or proof of a specific stealth ability. (Chapters 91–103, 114, 127, and 412)

Relationships

• Aengus Degaro: Yu begins with reverence mixed with caution, and Aengus uses Darkness Haki to ensure that he will not betray him. Their relationship develops into trusted service as Aengus repeatedly delegates sensitive logistics, personnel selection, and military support to Yu. (Chapters 87–127 and 265–273)
• Sienna Alsker: Yu introduces himself to Sienna as Aengus's local butler, helps her father approach the new lord, and later serves beside both siblings as part of the senior demon command. (Chapters 96–118, 265–273, and 340)
• Donna: Yu and Donna serve in the Dark Valley mansion and exchange surprised observations about Aengus and Bella's growing intimacy. Their scenes establish professional proximity, not a romantic or formal partnership. (Chapters 106–107)

Items

• No individually named personal item is assigned to Yu. He temporarily carries demon cores, manages treasury supplies, and participates in distribution, but these are institutional resources rather than equipment identified as his own. (Chapters 91 and 127)