- Born: 1775/7/8 (first Masafusa); c. 1772 (replacement Masafusa)
- Died: 1777 (first Masafusa); 1827/7/30 (replacement Masafusa)
- Other Names: 池田政恭 (Ikeda Masayuki)
- Japanese: 池田政房 (Ikeda Masafusa)
Ikeda Masafusa was a daimyô of Ikusaka han, a branch domain of Okayama han. He died at age three, after becoming lord of the domain, but was then replaced by a cousin, who took on the identity of the late Masafusa.
Masafusa was the fourth son of the previous daimyô, Ikeda Masasuke. Because his older brother predeceased him, upon the death of their father in 1776, two-year-old Masafusa became daimyô of Ikusaka. He died the following year, but this was never officially reported to the Tokugawa shogunate.
Ikeda Tetsujirô belonged to the main Ikeda clan family of Okayama. He was six years old when three-year-old Masafusa died, but Tetsujirô's birth had never been officially reported to the shogunate. Upon the death of young Masafusa, negotiations and arrangements were made, and Tetsujirô was sent to the domain's residence in Edo. He was then taken back to Ikusaka by Ikeda Shinmeiin, Masafusa's mother, who raised him as her own. When he was older, "Masafusa" changed his name to Masayuki.
The deception is detailed in Ikeda family records, but is absent entirely from Tokugawa records, such as the Kansei chôshû shokafu, which lists only a single Ikeda Masafusa ruling as Lord of Ikusaka from 1776 until his retirement in 1822. Tetsujirô, now known as Masayuki, passed on the position of daimyô to his son Ikeda Masanori, and died five years later, in 1827.
- "Ikeda Masayuki." Digital-ban Nihon jinmei daijiten デジタル版 日本人名大辞典. Kodansha, 2009.
- Roberts, Luke. Performing the Great Peace: Political Space and Open Secrets in Tokugawa Japan. University of Hawaii Press, 2012. p88.
- By traditional age calculation, which counts the number of calendar years (including partial ones) in which the individual has lived.