Lawrence "Mr. Cool" is a Chinese student at Horace Green Prep School and is a member of the class that Dewey Finn starts teaching as a substitute teacher under the name of Ned Schneebly. He played the piano in the school music class, and was the keyboardist of the class' School of Rock band. 

Polite, proper, mild-mannered and well-behaved to a fault, Lawrence obeyed his substitute teacher and became the band's keyboardist without question. However, he was at first worried that he was not cool enough to be in the band. He worried that he just wasn't cool because not many other students want to talk to him. But "Mr. S" assures him that he was cool enough for the band and that when he becomes a part of a rock band, he could become very popular in school.