Hyakubanme no Saru is adapted from Ken Keyes, Jr.’s 1981 book of the same title, which itself draws on a 1952 experiment conducted on the southern Japanese island of Kojima. The experiment demonstrated that once one monkey learned to wash its food, it could teach the behavior to other monkeys. Keyes suggested that when a certain number, an arbitrary figure of 100, had mastered the skill, the remaining monkeys seemed to acquire it spontaneously, and the same phenomenon appeared with a different group of apes on another island. Keyes used this apocryphal tale as a parable for the antinuclear movement, presenting it as proof that change would come if enough people joined forces.