Ten'ō Shishimaru is a ninja of hybrid heritage, born to human mother Sayo Momochi and an extraterrestrial father. Raised within the Momochi clan under the name "Ten'ō," signifying his celestial origins, his exceptional skill was recognized among his peers. He developed romantic feelings for fellow ninja Oyu. Her death during a mission—killed by the immortal warrior Ginnai Doma or, in some accounts, as part of a deceptive ploy by his grandfather Sandayu Momochi—became a pivotal trauma, hardening his resolve and fueling his pursuit of vengeance. Early confrontations with Ginnai Doma, an unkillable cyborg samurai serving warlord Oda Nobunaga, resulted in catastrophic losses. Shishimaru witnessed the slaughter of his comrades and Oyu, surviving grievous injuries only to be rescued by rival Koga ninja operatives, Hayabusa and Kojiro Ryuzuki. This forced him into a reluctant alliance with the Koga clan, marked by distrust and ideological clashes, particularly with Hayabusa. Their collaboration aimed to develop strategies against Ginnai and Nobunaga's forces, augmented by advanced weaponry, robotics, and extraterrestrial technology far beyond the Sengoku era's capabilities. During a critical battle against Ginnai, Shishimaru severed the cyborg's head using Ginnai's own katana, revealing his robotic physiology. Ginnai initiated a self-destruct sequence, triggering a nuclear-level explosion. Shishimaru lost his right arm in the blast but was saved by the intervention of the Black Lions, an extraterrestrial faction opposing the interdimensional White Devils. They provided him with a functional prosthetic arm and integrated him into their ranks, expanding his mission beyond personal vengeance to combating the White Devils, who sought to eradicate all sentient life across timelines. As a Black Lion operative, Shishimaru engaged in chronal conflicts, including a 23rd-century campaign against cyborg recreations of historical figures like Billy the Kid and Zhang Fei, engineered by the White Devils. He later confronted Ulysses and a resurrected Ginnai Doma during an assault on the White Devils' stronghold. After the Black Lions' spaceships destroyed Ginnai's body, his surviving head vowed retaliation—a detail only Shishimaru witnessed. The narrative concludes with him joining Hayabusa and the Black Lions on a cosmic campaign against the White Devils. Throughout his journey, Shishimaru evolved from a revenge-driven loner into a tactical leader capable of coordinating with former adversaries. His resilience endured physical dismemberment, psychological trauma, and adaptation to interstellar warfare, maintaining his commitment to protecting humanity from existential threats.