Yuuki Kouichirou (結城浩一郎, Yūki Kōichirō?) is the older brother of Yuuki Asuna and would have been one of the 10,000 players to be trapped in Sword Art Online, if he did not end up going on a business trip on the first day of the game's official service.
Kouichirou, like Asuna, went to a private school selected by their parents and, without a hitch, constantly retained excellent results. He was later employed to work in his father's company, RECT Inc. Due to his connections, he was able to acquire a copy of Sword Art Online. But, he was called to an overseas business trip on the very first day of the SAO's official service, preventing him from trying the VRMMO game on its first day. Because of this, his sister Asuna ended up asking him to borrow his NerveGear for merely a day, as she felt a desire to peek into a world she had never seen before. Due to the events of the first day of the official service of SAO, Asuna was trapped in the game for the next two years, bound by the NerveGear of her older brother.