Shuji Kato (修二佳人), hailed as the Professor (教官, Kyoukan), was the former Vice Kidō Chief of the Kidō Corps, who hailed from Nanashi's World. He is the older brother of Miyoko Kato, the brother-in-law of Rōnin Shiba, and the uncle of Kentaro Shiba. He served under Kaien Shiba as the Kidō specialist of his task-force during both of Arturo Plateado's invasions. He also fought alongside Kenji Hiroshi during the Tower of Night Incident, which saw him, his sister, and the Kudō twins trapped within the Tower. When Kaien and Kenji destroyed the Tower it returned to the world of its origin, taking Shuji and company with it. He spent the next few years trapped in Hueco Mundo before miraculously being reunited with Kentaro and Kaien.