Tanaka Tosa (田中 土佐, September 7, 1820 – October 8, 1868) was a Japanese samurai of the Edo period who was a retainer of the Matsudaira clan of Aizu. He served as a karō in the Aizu administration, and fought in the Boshin War.[1] Upon the entry of Imperial Japanese Army forces into the Tsuruga Castle town, he led an effort to halt their advance. Upon defeat, he followed fellow karō Jinbo Kuranosuke into a nearby doctor's house, and committed seppuku.