Seiko has a phlegmatic personality with a highly uncouth manner of speech. At the same time, she is selfless and empathetic to help others in need if its within her power, with the greatest example being her taking people in her house if they need a place to stay. As such, she follows the concept of "being in it together". Of course, she has a particularly soft spot for her lover. Despite being a grandmother, Seiko has the appearance of a slender woman in her prime.