The oldies are Otokotchi (female) and Ojitchi (male.) When they mate, their child will grow up to be Oyajitchi (male.) Oyajitchi can mate with any normal female adult character.
Note: On the TMGC+C (Japanese-language model with a color screen,) Otokotchi and Ojitchi's child can be either male or female (Gorippatchi.)