自分が「実の(じつの)母親と祖父との不倫(ふりん)の関係で生まれた子供」であるという秘密

'A Dark Night's Passing' (Anya Koro) is a monumental masterpiece of Japanese 'I-novels' written by Naoya Shiga from the Taisho to the early Showa period. The protagonist, Kensaku Tokito, discovered the harsh secret of his birth—that he was 'a child born of an illicit relationship between his biological mother and his grandfather'—harboring intense spiritual suffering and distrust toward humans.