Haruki Shirogane serves as a Congressman in the clandestine organization Bifrost, engaging in its high-stakes governance simulation called Roundrobin. He commands extensive expertise in Roundrobin's regulations, inner workings, and tangible global repercussions.

A man in his 70s of average height and slender build, Shirogane has swept-back gray hair, a gray balbo beard, and dark eyes. He typically dresses in a gray suit, ivory dress shirt, and blue bowtie.

His personality exhibits cunning, shrewdness, and calculated patience, strategically biding his time before acting. As a high-ranking Bifrost Congressman, he is acknowledged as a supremely skilled Roundrobin player.

He shares a long-standing association with fellow Congresswoman Kyoko Saionji. Aware of her secrets and professing no hatred toward her, he nonetheless eliminates her from Roundrobin upon uncovering her deceit. Shirogane also maintains ties with Congressman Shizuka Homura, openly admiring Homura's acute intellect and manipulative prowess.

During the Tokyo gubernatorial election involving candidate Karina Komiya, Shirogane operates with Bifrost members including Saionji and Koichi Azusawa. This election becomes a nexus for Bifrost's covert manipulation of political and economic systems.

His name reflects facets of his role: "Shirogane" translates to "payment," while "Haruki" combines characters signifying "distant" and "prosperous."