Case 1: Kabuki stars are different.
Last month, the 38-year-old kabuki actor Kataoka Ainosuke held a press conference and admitted that he is the father of a boy who is now a fifth-year elementary school student. Ainosuke is not married to the boy's 43-year-old mother, and has not formally "acknowledged" (ninchi) the boy in his family register. Even if he did, the boy would still be indicated as "illegitimate" (hichakushutsu) since the actor has never been married to the woman.
This "hidden child" was revealed by the weekly women's magazine Josei Seven, though it's assumed that show biz reporters have known about him for years. The reason they decided to make the relationship public now is because Ainosuke is suddenly a star, owing to his high-profile stint as the replacement for Ichikawa Ebizo, who had to drop out of his New Year's performances in Kyoto after being injured in a bar brawl in November. Josei Seven says that Ainosuke kept his son a secret because when the boy was born, the actor, who is not from a traditional kabuki family, was still making his name and the notoriety might have ruined his career.