Younghee Mandlebom was Leonard's nemesis that was from Korea and Leslie's best friend. She ws usually mean to Leonard. But she actually cared for him, even showing that he had a crush on him at least twice. She doesn't want anything bad to happen to Leonard and does not appreciate it when he does something dangerous, scary, or foolish. However, even though she and Leslie were best friends, Younghee was secretly envious of Leslie's money and pretty looks like all the other kids (except Leonard).