TV-Series
Description
Born Higashidani Sanosuke in February 1860, Nagano Prefecture, he left his farming family at age nine to join the Sekihōtai militia fighting for imperial forces in the Bakumatsu. Deeply inspired by their captain Sagara Sōzō, he adopted the Sagara surname. The Meiji government later betrayed the Sekihōtai, executing them as scapegoats for financial failures and framing them as frauds. Sanosuke witnessed Sōzō's execution, surviving alongside Tsukioka Katsuhiro. This betrayal ignited his lasting hatred for the Meiji government and Ishin Shishi revolutionaries.

Consumed by rage and guilt, Sanosuke became a Tokyo mercenary under the alias "Zanza," wielding an oversized, blunted zanbatō to crush opponents. He prominently displayed the kanji for "evil" (惡, aku) on his jacket back, symbolizing his defiance against government hypocrisy and loyalty to the Sekihōtai's memory. His life changed after encountering Himura Kenshin, who defeated him and shattered the zanbatō. Learning of Kenshin's pacifist philosophy and no-killing vow, Sanosuke abandoned mercenary work. He joined Kenshin's group at Kamiya Dojo, becoming Kenshin's closest friend and physical protector despite ideological differences.

During the Kyoto Disturbance, Saitō Hajime's taunt about Sanosuke's weakness motivated him to travel to Kyoto to support Kenshin against Shishio Makoto. En route in Shimosuwa, he encountered Yūkyūzan Anji, a former Shishio ally and fallen monk. Anji trained him in Futae no Kiwami ("Mastery of Two Layers"), a technique delivering two consecutive strikes to shatter targets by bypassing material hardness. Sanosuke mastered it within a week using his right hand. This technique proved critical against Anji, now serving Shishio as the "Bright King." Despite respecting Anji as a mentor, Sanosuke defeated him to awaken him from his destructive path, later calling Anji the "God of Destruction" whose strength set his standard.

Sanosuke utilized bombs provided by Tsukioka Katsuhiro (now using the alias Tsunan) to destroy Shishio's ironclad warship Rengoku, aiding Kenshin's infiltration of Shishio's fortress. His actions cemented his role as Kenshin's "right arm" in battle.

Following Kyoto, Sanosuke remained with Kenshin's group. When Yukishiro Enishi faked Kaoru's death, triggering Kenshin's collapse, Sanosuke left Tokyo after failing to console him. He encountered his birth family in Shinano, discovering his mother dead and his father (Higashidani Kamishimoemon) and siblings living in poverty under oppression by former Ishin Shishi officials. Concealing his identity initially, he intervened to protect them, overusing Futae no Kiwami and permanently damaging his right hand. He adapted by employing dual-handed successive strikes to mitigate further injury. He rejoined Kenshin's group for Kaoru's rescue in Tokyo, contributing to Enishi's defeat.

To avoid arrest for assaulting government figures during his family's defense, Sanosuke departed Japan to travel abroad. He maintained contact via letters, eventually informing friends of his planned return. His signature "aku" symbol influenced others; Myōjin Yahiko adopted a smaller version on his collar upon reaching adulthood.

Sanosuke's personality blends brashness, loyalty, and moral complexity. He values authenticity over conventional morality, despising lies and hypocrisy due to his Sekihōtai experience. Though jovial and laid-back, he possesses a fiery temper in combat, relishing fights against strong opponents while avoiding weaker ones. He demonstrates perceptiveness in crises but often relies on others for complex analysis. His freeloading habits at Kamiya Dojo and Akabeko restaurant provide recurring comedic elements. Kenshin regards him as his most dependable ally, appreciating Sanosuke's willingness to physically confront him during emotional lows.