Ryohei Kuroiwa commands the Shibuya Police as its Chief. After Shibuya's displacement into a post-apocalyptic future, he leads the sole surviving public safety organization. His duty focuses on preserving order and peace within a city spiraling into chaos following this cataclysm. He holds a seat on the newly formed provisional government established to manage the crisis.

Personally, Kuroiwa employs a direct and bold approach to his role. This style frequently translates into forceful and overbearing conduct during interactions and decision-making. He demonstrates significant firearms skill, earning recognition from fellow officers for his gun proficiency. His methods and priorities occasionally clash with other provisional government figures, like Mayor Seiichirō Muta, who favors negotiating with the hostile entities called Revisions.