Founder and primary intellectual leader of the right-wing Japanese literary movement Nippon Roman-Ha. Yasuda believed that the actual reality of historical events was unimportant and that the emotions these events aroused in a person were more important than the actual events themselves.

Mishima first met Yasuda in 1943, but he found Yasuda to be too extreme in his views and his explanations of his ideas hard to follow. When the Second World War was over, Yasuda found himself on a lists of "literary war criminals" and by Novemver of 1945 he was finally purged by the General Headquarters of the American occupation government where he was blacklisted into forced isolation.