Takekiyo Matsunaga (died 1976) was a Japanese yakuza who served as an officer of the Yomei Alliance. He was one of the men behind the creation of the Yamato Mark II battleship, which became known as the "Secret of Onomichi" after World War II, and, in 1976, he was marked for death by Chairman Heizo Iwami as part of Iwami's effort to cover up the secret. Matsunaga begged Heizo's son Tsuneo Iwami for mercy, informing him of the secret. That night, before Tsuneo could intercede, Matsunaga was fatally stabbed by a masked Toru Hirose as he returned home to his son Takaaki Matsunaga with a model of the Yamato, which Takaaki treasured for the rest of his life. Hirose, feeling guilt for the murder of his aniki, adopted Matsunaga as his own son.