A boy falls to his death at school, but Ok Chanmi does not believe that her twin brother, Park Wonseok, committed suicide. Chanmi transfers to her brother's school, Yongtan High, and meets Ji Sooheon, who witnessed her brother's death.

The death of his parents forces a seven-year-old boy named Seo Hae Bom to move in with an adoptive family who have a young son of the same age named Jo Tae Seong. Seo Hae Bom is in awe of Jo Tae Seong – he considers the boy to be everything that he is not: tall, handsome, popular, caring, and worthy of love and attention. The diminutive Seo Hae Bom thinks himself inferior and is humbled by the kindness of the family that took him in.