Count Katsu Yasuyoshi (? ??) (born Katsu Yoshikuni (? ??); March 12, 1823 – January 21, 1899), best known by his nickname Katsu Kaishu (? ??), was a Japanese statesman and naval engineer during the late Tokugawa shogunate and early Meiji period.
Kaishu was a nickname which he took from a piece of calligraphy (Kaishu Shooku ????) by Sakuma Shozan.
He went through a series of given names throughout his life; his childhood name was Rintaro (???).
He was often called Awa (??) from his title Awano-kami (???) during the late Tokugawa shogunate and later changed his name to Yasuyoshi (??) after the Meiji Restoration.
Katsu Kaishu eventually rose to occupy the position of commissioner (Gunkan-bugyo) in the Tokugawa navy.
He is particularly known for his role in the surrender of Edo.