Zenzou Hattori is a highly skilled ninja originally from the Oniwabanshuu, the shogun's special forces. His father, the Oniwabanshuu's strongest leader who instructed members including Sarutobi Ayame, caused a strained relationship through his obsession with "kick the can" and selling Zenzou's JUMP magazine collection to buy porn DVDs. Standing 175 cm tall and weighing 59 kg, he has light-brown or dark-blonde hair covering his blue eyes and sports a goatee. He typically wears a dark blue ninja suit with a long scarf. His full face is rarely visible due to his bangs, though he is considered handsome when his eyes are revealed. He describes samurai as loyal "dogs" and ninja as independent "cats," reflecting his freelance work ethic after leaving the Oniwabanshuu. He takes on diverse jobs for money, often unrelated to ninja duties, like pizza delivery. He suffers from severe hemorrhoids, leading to recurring physical comedy involving injuries to his backside or aggressive "medication" applications by Sarutobi Ayame; he prefers topical treatments over injections. He also has a noted attraction to women considered unattractive by others. Ranked among the strongest ninjas with the title "Zenzou of Marishiten," he was trained by his father and excels with kunai, bombs, and swords, capable of fighting evenly with Sakata Gintoki. His hemorrhoids make him vulnerable to attacks targeting his lower back. He shares a rivalry-turned-friendship with Gintoki centered on obsessive devotion to Weekly Jump magazine. Their first major encounter involved fighting over the last copy of a Christmas Double Issue Akamaru Jump, inadvertently thwarting an attack; they later collaborate in multiple conflicts. His relationship with Sarutobi Ayame involves mutual bullying, often related to his hemorrhoids, but deep camaraderie; they trained under his father and frequently ally in battles. With Tokugawa Shigeshige, he shares a lifelong bond and profound debt, leading him to undertake morally complex missions for the shogun's sake. Initially opposing Gintoki during the Go-Ninja Arc to stop Elizabeth's rescue, his role evolves. In the Red Spider Arc, he rescues Gintoki from the sea after a near-fatal injury and saves Hinowa from attackers. He later assists Yorozuya in protecting Sarutobi Ayame during the Glasses Arc and manipulates Gintoki in the Scandal Arc as part of an elaborate prank. The Shogun Assassination Arc marks a pivotal development: after refusing Sarutobi's offer to rejoin the Oniwabanshuu, he meets Tokugawa Shigeshige, paralyzes Rotten Maizou, and seemingly beheads the shogun to end a war. He claims responsibility for the assassination to carry the "sin for eternity," though this act is later revealed as a ruse involving a body double. He confronts the Yato on a ship and escapes with Sarutobi after a battle with Takasugi's forces. In the Silver Soul Arc, he returns to Edo ahead of an Amanto invasion, leading the Oniwabanshuu with Sarutobi to defend the city. He entrusts Princess Soyo to Momochi Rappa before departing Edo, believing his presence would endanger her. Beyond the main series, he appears in the spin-off "Class 3-Z’s Teacher Ginpachi" as a Japanese history teacher, maintaining his hemorrhoid gag and chalk-throwing skills. His ancestor is based on the historical ninja Hattori Hanzou. He makes a secret appearance in Gintama's first ending theme "Balloon Gum." His original voice actor passed away.