Akira Nishikiyama was born in Tokyo, Japan on 8 October 1968, and he was orphaned at a young age. He was raised at the yakuza Shintaro Kazama's Sunflower Orphanage, where he, his biological sister Yuko Nishikiyama, and fellow orphans Kazuma Kiryu and Yumi Sawamura were adopted by Kazama. At the age of 17, both Nishikiyama and Kiryu (who nicknamed his friend "Nishiki") decided to join the Tojo-kai yakuza clan despite Kazama's initial steadfast opposition (once even resulting in a beating). The two best friends were attached to the Kabukicho-based Dojima-gumi in 1985, and Nishikiyama cultivated his image as a "ladies' man" in order to impress his superiors and earn their favor as he worked to advance through the ranks of the criminal underworld. During the late 1980s, Kazama would be arrested after being betrayed by his fellow Dojima-gumi lieutenants at the behest of their boss, Sohei Dojima, who had discovered that Kazama had been secretly undermining his power due to his opposition to Dojima's cruelty.
Empty Lot dispute
On 10 December 1988, the day after Kiryu was implicated in the murder of Taichi Kurihara (whom Kiryu had not killed), Nishikiyama brought Kiryu to the Kazama-gumi captain Osamu Kashiwagi, and Kashiwagi deduced that Kiryu had been framed for the murder, most likely by the lieutenant Daisaku Kuze, who sought to have Kazama expelled from the family so that he could take his place as captain. Framing Kiryu for a murder would reflect poorly on Kazama and provide the necessary grounds for his expulsion from the Tojo clan. Against Nishikiyama and Kashiwagi's advice, however, Kiryu decided to retire from the yakuza so that his actions in searching for the man who framed him would not reflect on Kazama. Nishikiyama remained loyal to his friend even after the Taihei Association boss Hiroki Awano pinned Nishikiyama down and attempted to force him to give up Kiryu's location, as the Dojima-gumi were ordered to begin a manhunt to assassinate Kiryu before he could unearth the conspiracy against him. Nishikiyama initially planned to kill Kiryu himself and spare him from the Dojima family, driving him to the woods, but he was ultimately unable to bring himself to kill his sworn brother.
Nishikiyama was later offered a promotion if he killed Kiryu, but he instead decided to join Kiryu and help him in his attempt to rescue his ally Tetsu Tachibana, only to find that Tachibana had been tortured to death while in Kuze's captivity. Goro Majima later beat Nishikiyama down after tracking him down and demanding to know where Kiryu was, as his lover Makoto Makimura (the late Tachibana's sister) was with Kiryu. Nishikiyama later took part in the war between the Kazama-gumi and the Dojima-gumi after Keiji Shibusawa - the new captain of the Dojima-gumi - attempted to purge the family of Shintaro Kazama's loyalists. Nishikiyama and Kiryu headed to stop Shibusawa from massacring the Nikkyo Consortium's members and killing Makimura at Sera's Ocean Serenade yacht at the Shibaura wharf. Nishikiyama caught up to Kiryu just as he was about to kill Shibusawa, tackling him and then convincing him to spare the lieutenant rather than cross the line of becoming a murderer.
Turn to darkness
Nishikiyama and Kiryu both rose through the ranks of the Tojo-kai over the next several years, and they were joined in Kabukicho by their friend Yumi Sawamura in 1990. On 30 September 1995, Nishikiyama killed Sohei Dojima after he kidnapped Yumi and attempted to rape her, but, as Nishikiyama's sister Yuko was dying, Kiryu decided to take the fall for Nishikiyama and serve out his prison sentence, while Nishikiyama was allowed to form his own family, the Nishikiyama-gumi, a privilege which was supposed to be granted to Kiryu instead, had it not been for Kiryu's arrest. Nishikiyama became the boss of the Nishikiyama-gumi in 1996, and, that same year, Nishikiyama was informed by his doctor that, if he could raise ¥30 million, the doctor knew a black marketeer who could arrange for Akira's dying sister to have a heart transplant. Nishikiyama assigned this task to Hitoshi Matsushige, who stole from shops in Kashiwagi's territory to raise the money. Kashiwagi later discovered Nishikiyama's culpability and beat him in his office, berating him for betraying Kazama's legacy. Kashiwagi let slip a comment that Kiryu would not have done the same, causing Nishikiyama to grow jealous and resentful towards Kiryu.
Matsushige later gave Nishikiyama the ¥30 million, saying that he had collected it from an indebted doctor. Nishikiyama learned that the doctor was the same as the one who had asked him for the money, and, when Nishikiyama arrived at the hospital, he learned that the doctor had fled, and was devastated, knowing that his efforts were in vain and that his sister would die. Nishikiyama decided to commit suicide at his office, but, when Matsushige arrived and disrespected him by again comparing him to Kiryu, Nishikiyama stabbed Matsushige with the knife he was planning to use to commit seppuku with. Nishikiyama ultimately decided that he would rise to the top, regardless of how many people he had to kill or betray along the way, including Kazama.
Fight for the Yen
In 2005, Kiryu returned to Kabukicho after his release from prison, and he found that Nishikiyama had started his own family and become cold and heartless. By then, the family was searching for ¥10 billion which had gone missing from the clan's private bank. Nishikiyama wished to get his hands on the ¥10 billion to ensure that he would become the Tojo-kai's next chairman. Nishikiyama - jealous over Kiryu's fame and Yumi's affection - attempted to assassinate Kiryu several times, including at the funeral of chairman Masaru Sera, who had been killed on Nishikiyama's orders. At the same funeral, Nishikiyama mortally wounded Kazama with a sniper rifle, attempting to frame Kiryu for Kazama's murder, and succeeding in causing Kiryu to be hunted down by his own clan. The shooting of Sera led to a gang war breaking out between the Nishikiyama-gumi, Kazama-gumi, and Shimano-gumi, and the Omi Alliance attempted to take advantage of the Tojo civil war to seize control of Japan's criminal underworld with the help of the corrupt politician Kyohei Jingu, now Yumi's husband (as Yumi had suffered amnesia about her past following her rape attempt).
When Kiryu discovered from Kazama - who was mortally wounded by a grenade thrown by Futoshi Shimano - that he had stolen the ¥10 billion to prevent it from falling into the hands of Jingu, who had used his closeness to Masaru Sera to try to steal and launder the money to fund his political ambitions. After discovering that the money was stored at the Millennium Tower (where the Empty Lot once stood), Kiryu and Yumi's daughter Haruka Sawamura - whose pendant held the key to the vault - headed to the tower, where Yumi, having recovered her memories, resolved to destroy the ¥10 billion with a bomb to end the war. Jingu then arrived with the Ministry Intelligence Agency (MIA) and Omi Alliance and attempted to take the money by force. Nishikiyama also showed up, intending on taking the money for himself. Nishikiyama challenged Kiryu to a final fight for Yumi's affection, but, after a bitter fight to the end, Kiryu defeated Nishikiyama. Jingu then attempted to kill Kiryu, but shot Yumi instead, causing an enraged Nishikiyama to take action. Seeking to redeem himself, Nishikiyama stabbed Jingu with a knife and pushed him into the vault and shot the bomb Yumi had planted, blowing up himself, Jingu, and the ¥10 billion in the procress. The deaths of Nishikiyama, Yumi, Jingu, Kazama, Sera, and Shimano in the civil war of 2005 ended the great conspiracy, and Kiryu was convinced by the detective Makoto Date to take care of the young, orphaned Haruka rather than return to prison.