She is the wife of Shuichi Aizawa and the mother of Yumi Aizawa.
She first appeared in episode eighteen when Aizawa arrives with a bruise on his head, mentioning he had a minor argument with her. This was because Yumi was very young and he seldom slept at home. She appears again at the end of the episode when she and Yumi spot Aizawa sitting on a bench in the park. Eriko asks if he will be joining them for dinner since she only bought food for herself and her daughter. Shortly after, when Aizawa starts crying, Yumi asks her mother why he is crying.
"Death Note: How to Read 13" mentions that both she and her daughter are often sad due to Aizawa's heavy workload.
