Following Katataka's death in early 1852, Katamori succeeded to the family headship at age 18. As the 9th daimyō, he was granted the title of Higo no Kami (肥後守), which was traditionally held by the daimyō of Aizu-han.[6] He also received the additional title of Sakonnoe-gon-shōshō (左近衛権少将; Lesser General of the Left Guard) from the Imperial court, and formally sent his thanks to the Emperor later that year. Furthermore, Katamori inherited the family's traditional seat in the tamari no ma chamber, where important matters of state were discussed in conjunction with the Senior Council.