Sechskies Drama Special (1997)

Kim Jae Eun is a student that gets high grades and is a nice person, her twin brother Kim Jae Deok unlike Jae Eun he gets bad grades and he's playful. Jae Eun is in love with his childhood friend Ji Won, Ji Won shares the same feelings but they can't get closer because Jae Deok is possesive of her sister and thinks that Ji Won doesn't deserve Jae Eun.