Like her sister in-law, Gian's aunt is a large built woman. She has slightly curly brown hair and wears lipstick. As Nobita said, she bears a resemblance to a monkey.
Normally, Gian's aunt is a mild-mannered woman but if offended (i.e. calling her monkey) she can be quite angry and short-tempered. She is also a righteous person, punishing Gian when he bullies his friends.