Shizue Suoh is the Suoh family matriarch the mother of Yuzuru Suoh and the grandmother of Tamaki. She is a powerful individual who rules her family and its financially successful businesses with an iron hand. Though her backstory is only marginally explored, it may be speculated that one reason for her hardened nature is the fact that she was widowed at a relatively young age and either chose or was forced into becoming a tough businesswoman.

The Suoh matriarch is said to be 70 years old, but remains sharp and on task when it comes to business matters. On a personal level, she appears to be rigid, cold-hearted and dismissive towards most people, but especially towards her grandson, who she calls "filthy child" because he is Yuzuru's illegitimate son with Anne-Sophie de Grantaine.