Tetsudō Hisakawa, universally nicknamed Poppo, stands as a core member of the childhood circle known as the Super Peace Busters. His given name fuses the kanji for "iron" (鉄) and "path" (道), while his surname Hisakawa translates to "long time river" (久川). Physically, he reaches 183 cm with a medium build, brown hair, and brown eyes. His childhood look featured a shaved head topped with grey fuzz, typically dressed in hoodies and track pants. As a teenager and adult, his signature style emerges: a lilac bandanna, layered shirts, olive pants, sandals, and a distinctive blue pearl necklace attached to a pouch worn around his neck. Extensive travel maintains his tanned complexion. In childhood, Poppo radiated energetic, friendly loyalty, idolizing group leader Jinta Yadomi and cherishing his inclusion despite feeling socially awkward. The group shattered after Meiko "Menma" Honma's death, prompting Poppo to abandon high school. He embraces a nomadic existence, funding worldwide journeys through transient jobs. When not traveling, he inhabits the group's old secret base as his home. Outwardly, he projects a cheerful, mellow, easygoing persona, often mediating conflicts within the group and passionately championing their reunification. Yet this demeanor conceals profound guilt stemming from witnessing Menma's fatal accident. Privately, he carries flowers from the accident site inside his pouch necklace, a tangible emblem of unresolved trauma. Poppo proves pivotal in reuniting the Super Peace Busters after Jinta reports seeing Menma's spirit. He becomes the first to openly dedicate himself to fulfilling her wish, interpreting her presence as a sign of unrest. Frustration surfaces, however, as he remains unable to perceive Menma directly, unlike Jinta. His emotional journey culminates during the group's reconciliation when he confronts his buried guilt, revealing the lingering trauma of witnessing Menma's death and his agonizing powerlessness to prevent it. This catharsis finally allows him to fully participate in helping Menma move on. Achieving significant personal stability in adulthood, Poppo co-founds an import business with Jinta. He distinguishes himself as the only Super Peace Busters member to marry and have children, establishing a settled family life years later.