It is referenced that he stuttered as a child in “The Life and Death of Yukio Mishima”, a biography: Fuente: The New York Times https://share.google/OqvxQhRM5zYul8bU2 But most importantly, this is addressed in his screened biography. “Mishima, a life in 4 chapters”A film from 1985. Here’s an extract from an analysis of the film itself: “As a boy, Mishima was afflicted with a paralyzing stutter, was weakly, was the target of bullies. The film's biographical sequences show him being advised by a friend who limps to exploit his own disability as a way of making himself attractive to women. Eventually these lessons take a turn: Mishima becomes a muscular body-builder, a paragon of surface masculinity, to attract men -- not so much as his lovers but as his followers or slaves. Their worship validates his supremacy and denies his deep-seated feelings of inferiority.”