From Muppet Wiki

Xiao Mei Zi is a character from Zhima Jie, the Chinese co-production of Sesame Street. Her name means "Little Plum".

Sesame Workshop description

Little Plum is a bright red, three-year-old monster, who loves to read books and listen to stories. Little Plum is very smart, quick, and curious. She is also innocent, naïve, extremely optimistic, and easily distracted. She tends to overlook messes and doesn’t mind her own messy hair. When Hu Hu Zhu gets confused, Little Plum remains levelheaded. Sometimes Hu Hu Zhu drives her crazy because he always wants to help her. She puts up with his huffing and puffing because he is such a good friend. Everyone else puts up with Little Plum’s extremely loud snoring.