Kimitake Hiraoka (平岡 公威, Hiraoka Kimitake, January 14, 1925 – November 25, 1970), known also under the pen name Yukio Mishima^[a] (三島 由紀夫, Mishima Yukio), was a Japanese author, poet, playwright, actor, model, film director, nationalist, and founder of the Tatenokai. Mishima is considered one of the most important Japanese authors of the 20th century. He was considered for the Nobel Prize in Literature in 1968, but the award went to his countryman and friend Yasunari Kawabata. His works include the novels Confessions of a Mask and The Temple of the Golden Pavilion as well as the autobiographical essay Sun and Steel. Mishima's work is characterized by "its luxurious vocabulary and decadent metaphors, its fusion of traditional Japanese and modern Western literary styles, and its obsessive assertions of the unity of beauty, eroticism and death".

Mishima's personal life was controversial, and he remains a controversial figure in modern Japan. Ideologically a right-wing nationalist who opposed the westernization of Japan, Mishima formed the Tatenokai, an unarmed civilian militia, for the avowed purpose of restoring power to the Japanese Emperor. On November 25, 1970, Mishima and four members of his militia entered a military base in central Tokyo, took the commandant hostage, and attempted to inspire the Japan Self-Defense Forces to overturn Japan's 1947 Constitution. When this was unsuccessful, Mishima committed seppuku.