Haruko Sakurai, Shinichi Sakurai's mother, possesses chestnut brown hair and brown eyes. She typically wears a watermelon-colored sweater over a plum shirt, paired with faded light blue pants and lilac shoes. Born Sengoku Haruko, she is married to Shirō Sakurai. Their children are Shinichi and a younger daughter, Nodoka Sakurai, born while Shinichi attended college.

Haruko radiates an outgoing and friendly personality, engaging in playful banter and teasing with friends. Her high intelligence and academic diligence drive her to prioritize studies and personal goals while maintaining a balanced approach to leisure and socializing. She proves a reliable friend, offering attentive listening and thoughtful advice when sought. Athletically inclined, she was an active member of multiple sports clubs during college, reflecting her energetic nature. Haruko values her friendships deeply, consistently making efforts to support those close to her despite her own commitments.