Seiichirō's nephew Daisuke Saiki (砕軌 玳透 Saiki Daisuke?) is also a wind magician, though not of Seiichirō's calibre. Saiki and Kamui initially do not get along very well, as the stoic and strictly by-the-rules Saiki was not completely convinced that Kamui was the one on which the fate of humanity rested; later, they understand each other better and become friends. Saiki lives to protect Hinoto, whom he seems to have affections for. In the manga, he is brutally decapitated by Fūma while protecting Hinoto; in the anime, he was killed by a powerful blast by Fūma.
In Tsubasa, he appears as Subaru's replacement as a fighter of the Tower faction in Tokyo.