Sechika Nobuyoshi served asō a bushō during the Sengoku and Azuchi-Momoyama periods. Nobuyoshi was a retainer of Kobayakawa Takakage. His surname is also pronounced as Suechika.
Nobuyoshi was born as the son of Sechika Kura-no-suke, a retainer of the Kobayakawa clan, and served Kobayakawa Takakage. Nobuyoshi’s name appears frequently in Kobayakawa family records under the name Sechika Saemon-no-jō. In 1570, Nobuyoshi built Hagura Castle in Hagura in Bingo Province and became its lord. He followed this by excavating irrigation channels and developing new plots of land for cultivation.
In 1582, Hashiba Hideyoshi attacked Shimizu Muneharu at Bitchū-Takmatsu Castle in an event known as the Battle of Bitchū-Takamatsu Castle. Nobuyoshi responded by leading reinforcements from the Kobayakawa clan and entered Takamatsu Castle as the commander of the forces. After Muneharu refused a proposal to surrender, Hideyoshi executed a plan devised by Kuroda Yoshitaka to flood the castle, whereupon the defenders faced precarious circumstances.
However, at the height of the attack, Hideyoshi learned that his lord, Oda Nobunaga, had killed himself in a coup d’état known as the Honnō Temple Incident on 6/2 of 1582, so Hideyoshi proposed that, in exchange for Muneharu taking his own life, Hideyoshi would spare the lives of the soldiers defending the castle. In the absence of any prospect that the Mōri would be able to help the defenders save the castle while under attack by flooding, Muneharu was forced to accept the offer. On 6/4, Nobuyoshi joined Muneharu, Shimizu Munetomo (Muneharu’s older brother), and Nanba Munetada (Muneharu’s younger brother) to commit seppuku while aboard a boat.
After his death at Takamatsu Castle, Nobuyoshi was succeeded by his eldest son, Sechika Mitsuhisa, who became head of the Sechika clan. On 6/18, Takakage sent a letter to Mitsuhisa praising Nobuyoshi for his act of valor and noting that he would never forget Nobuyoshi’s loyalty.