Mishima's Kochan we see from an early age, being unable to conduct his life on a frank and honest level; every action he undertakes and every experience he undergoes is filtered through the twisted and inverted stew of his mind. The real world acts only as stimulus for the narrator's self-deception, and because he is unable to avoid deceiving himself, he necessarily deceives everyone else, from the doctors to whom he lies about his health, to Sonoko, the girl he imagines himself not to love.
Kochan's inability to relate to the world except after it has been processed by his own eccentric way of perceiving it, is seen early in the novel. Indeed, his first memory is probably a created one: "No matter how they explained, no matter how they laughed me away, I could not but believe I remembered my own birth." (Mishima 2) Here we see for the first time the attitude which drives the novel: life, the universe, and everything for the narrator are products of his own mind. "Reality" as he perceives it has its roots in real events--he was, in fact, born; his existence is not just his own fantasy--but the event is twisted and mangled until it fits his own concept.
We can see the same sort of modification of reality in his "earliest [unquestionable] memory." (Mishima 7) He sees "a night-soil man, a ladler of excrement" coming down a hill. (Mishima 8)