Empress Longcheng, bearing the imperial dragon ("龍") family name, ascends the throne of the Taibai Empire as a girl-empress. She enforces her late father's expansionist agenda, driving a relentless war for unification despite internal strife and her own gnawing doubts about its human cost.

Her past holds profound trauma: three years prior, witnessing an assassin target her father triggered a catastrophic manifestation of hidden power. This uncontrolled surge killed both the attacker and her father, an event that irrevocably forged her. Family tensions define her court; her half-sister, Long Juan, is daughter to Lady Pang, who actively plots Longcheng's assassination to place Long Juan on the throne. This scheme culminates in Lady Pang's betrayal and subsequent execution by Longcheng. Long Juan displays no remorse, deepening the rift between the sisters.

Longcheng habitually escapes the palace in disguise to meet Pu Zhao, an enslaved engineer. Initially unaware of her true status, he befriends her. She later reveals her identity, bestowing upon him immunity, a noble title, and the role of Chief Engineer following his mentor's defection. Her dealings with Zhao intertwine genuine, almost childlike fondness with political maneuvering, frequently placing her personal desire for his company above his known rebel ties.

She commands immense latent abilities unleashed by emotional extremes, violently resurfacing when she faces betrayal or threat. After eliminating Lady Pang, she fully embraces this devastating power, showcasing her ruthless capacity to secure dominance. Her reign embodies stark contradictions: she questions imperial violence yet perpetuates it, craves authentic bonds with Zhao while wielding her authority over him, and grieves her father's legacy while actively extending the suffering it wrought.