Yasunari Kawabata had Parkinson's disease), a possible illicit love affair, or the shock caused by the suicide of his friend Yukio Mishima in 1970. Unlike Mishima, Kawabata left no note, and since (again unlike Mishima) he had not discussed significantly in his writings the topic of taking his own life, his motives remain unclear. However, his Japanese biographer, Takeo Okuno, has related how he had nightmares about Mishima for two or three hundred nights in a row, and was incessantly haunted by the specter of Mishima. In a persistently depressed state of mind, he would tell friends during his last years that
Yukio Mishima that all those deaths were in vain. In the final ten years of his life, Mishima wrote several full-length plays, acted in several films, and co-directed an adaptation of one of his stories, "Patriotism, the Rite of Love and Death." He also continued work on his final tetralogy, "The Sea of Fertility" ("Hōjō no Umi"), which appeared in monthly serialized format from September 1965. Mishima espoused a very individual brand of nationalism towards the end of his life. He was hated by leftists, in particular for his outspoken commitment to bushido, the code of the samurai, and by mainstream nationalists