Kaihō Tsunachika served as a bushō during the Sengoku period. He was a retainer of the Azai clan. He was also known as Zenemon.
Based on the fact that Tsunachika’s fourth son returned to farming in Uryū in Ōmi Province, this location is regarded as the homeland of Tsunachika. Together with Akao Kiyotsuna and Amenomori Kiyosada, Tsunachika was one of the Three Generals of the Azai. Tsunachika served as a senior retainer and military commissioner for three generations of the Azai clan. In 1573, Tsunachika is considered to have been killed in action when Oda Nobunaga attacked and toppled Odani Castle.
Tsunachika was a brave and intelligent bushō. Aware of his capabilities, Hashiba Hideyoshi had to acknowledge that Tsunachika was the instructor of Hideyoshi’s own military tactics.
A portrait painted by Tsunachika’s grandson, Kaihō Yūsetsu, with a tribute added by Yūsetsu’s son (Yūchiku) that says “Portrait of the Yūshō Couple” was cited as evidence in historical accounts that Tsunachika died in battle against the Oda in 1573. However, a letter of commendation made in the first month of 1535 (forty years prior to the painting) states that Tsunachika died during a nighttime attack led by Azai Sukemasa on the residence of Taga Sadataka, a retainer of the Kyōgoku clan. The contradiction likely owes to Yūchiku confusing Tsunachika and Tsunachika’s eldest son who had the same name of Zenemon.
In primary sources, Kaihō Zenemon is only abbreviated to Kaizen, and it cannot be determined that this refers to Tsunachika.