Kikue Hanai is the mother of Azusa Hanai and a big baseball fan as she and her husband even read the high school baseball newspaper. She is seen in episode 13 when she calls Ren's mother on the phone.
She calls her son "Hanai" because he doesn't like it when she calls him Azusa in front of his friends.
She also has twin daughters, Haruka and Asuka Hanai, who are Azusa's little sisters. She claims her husband has absolutely no interest in baseball.
She's very social, talkative and opinionated. She and her son have a good relationship where they talk about all sorts of things. She calls him Oniichan (big brother) or Azusa (which he doesn't like).
Her strong personality enables her to withstand the rude attitude from her only son.