Sonoko is fourteen years old with ashen-blonde hair and hazel eyes. She's wearing her Assault Lily crossover uniform. Sonoko is old friends with fellow Hero Club member-Mimori Togo. Sonoko is friends with the rest of the Hero Club-Yuna Yuki, Fu Inubozaki, Itsuki Inubozaki, and Karin Miyoshi. Sonoko calls Yuna "YuYu", Togo "Washi", Fu "Fumin", Itsuki "Itsun" and Karin "Niboshi". She is hyperactive, yet always sleepy. She has weird dreams and has a stuffed animal named Sancho.