Natsuko Mihama is the general manager of the fashion brand Dear Crown, maintaining a close professional association with June Amou. Her personal life revolves around her family as the mother of Kouji Mihama and the widow of the deceased Takeyuki Mihama.

Physically, she has short black hair featuring a single strand swept to the right and two small strands sticking up at the back. Her forest-brown eyes and a small mole under the left side of her lip are distinctive. She typically wears a fishtail black skirt with a long-sleeved purple top and finely defined makeup.

Her background involves a tragic connection to Gen Suzuno rooted in her husband Takeyuki's death. Takeyuki previously played in a band with Gen Suzuno, and Natsuko holds Gen responsible for her husband's demise. This unresolved grief and bitterness fuel her actions, particularly her vehement opposition to her son Kouji's romantic relationship with Gen's daughter, Ito Suzuno. She actively works to end their relationship due to her hatred for Gen, despite Ito's lack of involvement in the past incident.

Her surname, Mihama, combines the characters for "god" (神) and "beach/seashore" (浜). Her given name, Natsuko, incorporates the meanings "apple tree" (奈), "haven/port" (津), and "child" (子).