Tetsudo Hisakawa, universally called "Poppo," belonged to the childhood circle known as the Super Peace Busters. As a boy, he sported a shaved head and favored casual wear like hoodies and track pants. He openly admired his friend Jinta Yadomi, frequently labeling him "amazing" or "cool," and felt thankful for his inclusion in the group, aware of his own social awkwardness. During their youth, Poppo witnessed the accidental death of their friend Meiko Honma. This event left a deep mark, though he initially masked his trauma behind a cheerful facade. In the years after the tragedy, he left school and journeyed the world, funding his travels with various part-time jobs. When in his hometown, he resided in the group's childhood secret base. As a teenager and young man, Poppo projected a worldly, mellow, and easygoing personality. Learning of Meiko's ghostly reappearance, he actively sought to reunite the Super Peace Busters, readily believing Jinta could see her. He was the first to directly promise Meiko he would help fulfill her wish to move on and often mediated group conflicts. Despite his outwardly carefree demeanor, he secretly carried intense guilt over his role in Meiko's accident for years. He maintained physical tokens tied to his grief, wearing a pouch around his neck containing flowers that bloomed near the site of Meiko's death, symbolizing his unresolved trauma. His typical attire included a lilac bandanna, layered shirts, olive pants with a blue pearl necklace attached, and sandals. Later in life, he co-founded an import business with Jinta. According to a 10th-anniversary stage event, he eventually married, had children, becoming the only Super Peace Buster to start a family. His given name, Tetsudo, combines the characters for "iron" and "path," reflecting his journey, while his surname, Hisakawa, means "long time river."