Sonia is a cheerful and polite girl with a great interest for Japanese culture. She is very kind and thoughtful, and she cares deeply for her friends, being very protective to those she holds deep connection to. She is also rather naive. Sonia is fascinated with serial killers and the occult and has actually stated that she likes Friday the 13th. Sonia is a rather calm person during the Killing game, as she is one of the few participants to not panic as much, compared to the others, but admits that she is desperate to go home to her people while breaking down in tears. She states that she does not fear death, but she also won't let herself be killed nor kill any of her friends. One of Sonia's behaviors in studying Japan is to act like a normal girl. She firmly states that she wishes to be a normal Japanese girl and have friends of her own status.

Her official English voice actress is Natalie Hoover.