Zieg Ishi (ジーク石, Ishi Sieg), formerly Zieg Yoso (ジークヨーヨー, Yōsō Sieg), is a powerful Arcanist who changed his name to distance himself from the mistakes he made in the past that brought about his sisters death. He bears a personal grudge against the late Genryūsai Shigekuni Yamamoto and Mayuri Kurotsuchi, by extension, any Shinigami following the Soul Society. This grudge also seems to carry over to Yamamoto's students, as Zieg has little love for the Gotei 13's current Head-Captain Madoka Mizuki. In fact, the only Shinigami he openly trusts to any degree are Kenji Hiroshi and those he partners within the Ryū Order, others being Shigeru Yuudai because of a past meeting.