Prime Minister Shiramizu serves as Japan's elected leader in the series, presenting a distinguished figure with fair skin, swept-back black hair, and rectangular glasses. He consistently dresses in a navy blue suit with a gray tie, light gray dress shirt, navy blue pants and shoes, and a yellow lapel pin.

His demeanor remains poised and stern, marked by dignified speech and a willingness to openly criticize peers, exemplified when he issues a direct warning to Barbara Rose during Anima City's 10-year anniversary. A profound distrust of Beastmen defines his character, driving him to infringe on their rights for even minor personal or political advantages.

Shiramizu collaborated with Rose to establish Anima City as a Beastmen sanctuary, yet his actions consistently prioritize human interests and control. During the anniversary, he offers Rose congratulations while delivering a stern ultimatum: demanding strict population control and explicitly threatening violent measures if any Beastman loses control. This reinforces his unwavering focus on containment and suppression over genuine coexistence.

His role persists without evolution, centered on exercising political authority and perpetuating human-Bestman tensions.