Peruhiko Saijō serves as a secondary character in the Earth Deliberation Meetings, joining protagonist Ponta Ninomiya and companions Piisuke Kurosaki and Monyokichi Ootori. These meetings address global issues through consistently simplistic discussions lacking logical depth. When debating declining birth rates, Peruhiko and the group propose scattering birdseed to attract storks, mistakenly believing storks deliver babies. Confronting deforestation or ozone depletion, they suggest reductive solutions like "stop destroying forests" or wearing earplugs against noise pollution.

During TPP deliberations, Peruhiko collaborates in fabricating tangential narratives around the acronym, co-creating a nonsensical story about a fictional Takahashi. His participation consistently reflects earnest engagement with flawed reasoning, driven by naive enthusiasm rather than malice or intentional absurdity. No individual character arc, background, or personal development for Peruhiko Saijō is documented. His role remains strictly confined to group activities—primarily the Earth Deliberation Meetings—without elaboration on family life, personal history, or external relationships.