Rinroku Kaisho reigns as chairman of JJ System, a corporation monopolizing Tokyo's postwar communication infrastructure and earning him the title "Media King." He advises government bodies like the Public Prosecutor's Office and National Police Agency, leveraging his information networks to manipulate public perception and official investigations.

His backstory includes a deceased spouse and a daughter, Rie Kaisho, who disapproves of his methods. Despite immense wealth, he exhibits unconventional habits such as eating peanut butter straight from the jar.

In "Un-Go episode:0 Inga-ron," Kaisho manipulates events after the Bettenou cult incident. He falsely accuses Shinjuro of murdering Myoushin Oono and fabricates a new identity—"Shinjuro Yuki"—to erase Shinjuro's past, reflecting his pattern of obscuring truth for perceived societal stability. Post-credits, he observes Bettenou on a malfunctioning live broadcast, reaching toward the screen—suggesting his continued fascination with supernatural forces.

Evidence further implicates Kaisho in instigating the conflict that led to Shinjuro and Inga's meeting. He assigned Makiro Serada to escort volunteers into a warzone, resulting in their deaths; the subsequent cover-up fueled public support for military mobilization. Kaisho presents a courteous exterior while exercising ruthless pragmatism, prioritizing control over transparency.