Natsuka is the eldest son of Emperor Natsumihiko and his lawful wife Yuzemi, making him the half‑brother of the crown prince Wakamiya. Intelligent and possessing the dignity befitting an elder son, he was initially considered the most promising candidate for imperial succession. However, when Wakamiya was born bearing the mark of a true golden crow, the priests chose the younger half‑brother as the servant of the Mountain God instead. Following a prolonged dispute over the succession, Natsuka was forced to renounce his claim and entered the priesthood, becoming a monk. Despite his religious position, he remains a well‑built and commanding presence who commands a significant political faction known as the Natsuka sect, which draws its support from his mother’s South Family lineage. His relationship with Wakamiya is strained by the rivalry over the throne and the circumstances of their birth; Natsuka’s mother, the empress, and his own adherents are openly opposed to Wakamiya’s rule. Throughout the story, Natsuka acts as a key antagonist within the imperial court, using his intelligence and influence to challenge the prince’s authority and further his own agenda. He is attended by the loyal bodyguard Rokon and is advised by Atsufusa, a retainer five years older than Wakamiya. His sharp intellect and political maneuvering are his most notable abilities, though he also demonstrates the physical presence expected of a warrior‑monk. Character development sees Natsuka grappling with his lost birthright and the resentment that fuels his actions, though the narrative leaves room for his strategic cunning to evolve in response to the unfolding political crises.