Character: Kim Taeyeon: 7 years ago was a high school student who falls in love with her teacher, Tiffany Hwang. she studied hard and worked hard so that it can fulfill a promise to her teacher to become a rich and successful. Tiffany Hwang: 7 years ago was a high school teacher, she resigned as a teacher because she doesnt want to interfere with her love for Taeyeon future.