Prince Sirius Hiver reigns as a central figure from the otome game "Starry Love Astrolabe," holding his position in the Kingdom of Iver with an unconventional and straightforward personality that defies royal norms. His black hair remains consistent in all official depictions. Originally designed as the primary romantic target for heroine Kris, Sirius unexpectedly redirects his profound attraction toward Diana Diafell, the game’s designated villainess. This deviation from narrative expectations forms the core conflict of his journey.

Across all documented events, Sirius pursues Diana with unwavering persistence. Diana deliberately employs seductive tactics to repel him, believing such "impurity" would contradict his presumed admiration for purity and avert their doomed romance alongside the world’s destruction. Contrary to her intentions, Sirius responds with intensified desire, deepening his emotional attachment despite her manipulative efforts. His motivations for defying the game’s intended path remain unexplained, though his fixation on Diana persists unaltered.

Sirius’s development remains exclusively tied to his interactions with Diana and reactions to her strategies. Episodic titles like "Why? The Prince Won’t Give Up on the Villainess!" and "I Really Like the Villainess, I Love Her" reinforce his singular romantic focus throughout the timeline. His narrative concludes without resolving the central tension of avoiding the "bad ending," leaving both his ultimate fate and the world’s stability unresolved.