She's your overprotective mother with a dark side

Based on descriptions of her youth, Seiko appears to have traits associated with sociopathy, feeling emotionally distant to everyone that she interacts with. As a result, she is unable to love or care for anyone, including her own son and other relatives. In certain instances, the people around her describe her as having a face that entails a hatred or indifference to everyone, including herself, which persuaded her into having a perpetual smile