'Maru' means circle or 'O', and signifies a correct answer. In Japanese, 'badtz' (batsu) is a term for 'X', the cross signifying a wrong answer. He is one of the few Sanrio characters that is marketed to both males and females.
His birthday is April 1 (April Fool's Day). Bad Badtz-Maru ( バッドばつ丸, Baddo batsu maru) is a male penguin with spiky hair.
