Akira Kiyosato is a figure from the past whose actions have a lasting impact on the protagonist, Himura Kenshin. He is introduced as the second son of a retainer to the shogun, born into a family of modest standing. Hailing from Edo, he was the childhood friend and fiancé of Yukishiro Tomoe. Their relationship was deep-rooted, having met as children and fallen in love by the time they were teenagers, with their marriage already planned.

Akira's defining motivation was his desire to provide a secure and respectable life for Tomoe. Feeling that his position as a second son of a low-ranking samurai family was insufficient to make her proud, he postponed their wedding. Seeking to prove himself and gain a better status, he left Edo for the politically turbulent city of Kyoto during the final years of the shogunate. There, he joined the Mimawarigumi, a shogunate police force, and became a bodyguard for a high-ranking samurai named Shigekura Jubei. This decision, born of love and ambition, tragically placed him in the path of the assassin known as Hitokiri Battosai.

In terms of personality, Akira was remembered by Tomoe as a kind, caring, and hardworking man, though not particularly talented as a swordsman or in artistic pursuits. He was well-liked by those around him. His deep love for Tomoe is a central facet of his character; she was his final thought as he lay dying. This love also extended to Tomoe's younger brother, Enishi, whom Akira cared for as if he were his own sibling.

Akira's role in the story is pivotal despite his limited screen time, as his death directly leads to the creation of the first half of the cross-shaped scar on Kenshin's left cheek. In the first year of the Genji era (1864), after a night of drinking with his charge and a fellow bodyguard named Ishiji, the group was confronted by Himura Battosai on an assassination mission. After Battosai swiftly killed Ishiji and Shigekura Jubei, Akira was left to face the hitokiri alone. Though far outmatched, he fought with a desperate tenacity and a fierce will to live, crying out that he could not die there. In his valiant but futile struggle, he managed to inflict a deep, lasting vertical cut on Battosai's face, the first of the two wounds that would become the famous cross-shaped scar. As he bled out on the ground, weeping over his lost future with Tomoe, Battosai delivered the killing blow. In a rare moment of reflection, the assassin commended Akira's strong will to live and prayed that he would find happiness in his next life.

The significance of Akira Kiyosato is not in his swordsmanship or his personal history, but in the profound psychological impact of his death. His desperate struggle made the young killer Kenshin pause and consider the weight of each life he was taking. The scar he left on Kenshin's face served as a permanent, physical reminder of this encounter. This event set the stage for the subsequent tragedy involving Tomoe, who would later marry Kenshin as part of a revenge plot, ultimately leading to her death and the completion of the scar. Akira's final moments, filled with a sorrowful love for Tomoe, directly contributed to the emotional turmoil that would later drive Kenshin to swear his famous vow to never take another life. His presence is felt most strongly in the Remembrances arc, where the truth of his relationship with Tomoe is revealed, and his influence continues to haunt Kenshin's past. He also appears in flashback sequences in the live-action film Rurouni Kenshin: The Final, where he is portrayed by actor Kubota Masataka.