Tetsudō Hisakawa, nicknamed Poppo in childhood, sported a completely shaved head with only grey fuzz remaining. He typically wore a blue short-sleeved hoodie, blue-green track pants, and yellow shoes.

As a child, Poppo exhibited social awkwardness and felt deep gratitude toward the Super Peace Busters for accepting him despite his difficulties fitting in. He idolized Jinta Yadomi, frequently calling him "amazing" or "cool," and saw him as a natural leader, drawn to Jinta's charisma and the group's inclusion during his own social struggles.

Poppo witnessed the incident leading to Meiko Honma's accidental drowning. As the sole witness, he carried profound guilt for failing to save her, a trauma that heavily shaped his future. This guilt fueled an adult tendency to avoid painful memories, yet paradoxically led him to live in the group's childhood secret base, clinging to the past.

Within the Super Peace Busters, Poppo often mediated conflicts and maintained harmony, a role that continued into adulthood. He consistently supported efforts to reunite the group and readily believed Jinta's claims of seeing Menma's ghost, reflecting his enduring loyalty.

Official extended media, like the "10 Years After" stage event, depicts Tetsudō as the sole Super Peace Busters member to marry and have children, marking a path toward familial stability. This contrasts with his earlier adolescent rootlessness, where traveling and part-time jobs served as an escape from unresolved grief.