Mrs. Kaidou

 is the mother of Shun, Toki, and Sora.

Background
She is an intelligent woman who wears glasses and is tough, enthusiastic and disciplined when it comes to her son's education. Education is highly prioritized for her, which can be shown by her telling her child that studying daily will get him an instant ticket to a first class university and forcing Shun's friends, Kusuo and Riki, to complete several work books. She was once a career woman in the prime of life but turned into house-wife the moment she got married.

Trivia

 * Her husband is alive, he is mostly busy with work, but he has not been seen.
 * Despite prioritizing her son Shun into being educationally driven, he is not very bright and continues making mistakes whenever he is boasting about himself. This brings to mind the phrase "never confuse education for intelligence."