Riku is a mysterious young financier of Shikabaneya, a demon bounty-hunting business owned by Jyuubei, the corpse dealer.
Little is known of Riku's history or his nature, other than he is at least 200 years old and has been Lord Kirinmaru’s loyal retainer for most, if not all, of those years, apparently having been raised by the demon lord’s older half-sister Lady Zero. When Lord Kirinmaru received word that his rival Inu no Taishou, the dog-demon ruler of the Western Lands, had received fatal injuries during an epic battle with the dragon-youkai Ryuukotsusei, he tasked Riku with gathering medicine to save him before his impending death. Though Riku managed to acquire the medicine needed to save Inu no Taishou’s life, he arrived to late; the great dog demon having sacrificed his life to save his human lover Lady Izayoi and their half-demon son Inuyasha in a final battle with the human samurai lord Takemaru of Setsuna. By the time Riku arrived, Lady Izayoi’s mansion was already set ablaze and Inu no Taishou and Takemaru dead inside, which means that he realized that he was too late. When Riku delivered news of Inu no Taishou’s death to Lady Zero, who was secretly in love with her brother’s rival, she was so overcome with grief that she made a desperate wish upon the sacred Shikon no Tama to be rid of her grief forever. Watching her as she made this wish, Riku would witness the creation of the seven Rainbow Pearls, which contained Lady Zero’s lost emotions within them.
Sometime later, Riku became a pirate though he set a standard of never robbing women, children, or those in need. While it’s not known when he first met Jyuubei, he became his patron and the main financier and client of his demon bounty hunting business, gaining his respect and loyalty by using his powers to reward him with much wealth.
