Megu Yokosuka, also called Meg Yokosuka, is the younger sister of Jou Yokosuka. Half-Japanese with blonde hair, blue eyes, and a distinctive facial mole, she was born on July 7, 1942. Abandoned by their mother in childhood, Megu and Jou lived in an orphanage until an old woman took them in, a period during which Jou suffered sexual abuse.

After Jou was sent to a disciplinary school, twelve-year-old Megu knowingly accepted adoption by a man notorious for preying on young girls to avoid burdening her brother. She endured years of sexual abuse before escaping at fifteen. Supporting herself, she worked as a hostess in a cabaret club. Initially, Megu rejected Jou's attempts to rescue her, seeking to protect him from further trouble. They reunited years later, and she supported his pursuit of a singing career, recognizing his talent. Megu also assisted Lily, a maternal figure, with her restaurant.

Megu developed a relationship with Tadayoshi Tooyama, known as Soldier, who shielded her from criminals seeking to exploit her. They married, and she remained loyal during his imprisonment for crimes he took responsibility for to protect another. Following Soldier's release, they started a family, with Megu becoming pregnant.

Throughout her life, Megu fiercely valued her independence while deeply cherishing trusted connections. Her experiences of trauma and resilience forged a protective nature, first toward her brother and later her husband. She participated alongside Jou and Soldier in fulfilling a promise to the deceased Rokurouta Sakuragi, finding closure and personal stability in her later years.