S1, E1: Yun Jiwon, a gym teacher at Dokmok High, wakes up troubled by a dream of being abandoned at Namsan Tower. Her grandfather, the school chairman, is in danger of losing the school foundation to his bitter rival, Seok Gyeongtae. He plans to take over and build a golf course nearby and advises his son, Seok Jiwon, to take over as chairman. Despite their childhood rivalry, Yun Jiwon and Seok Jiwon developed feelings for each other in high school and even ended up dating after losing a bet. Seok Jiwon is shocked to hear that Yun Jiwon doesn't remember him and seeks her out on his first day at school. Haunted by yet another nightmare, Yun Jiwon confuses him as the eighteen-year-old Seok Jiwon from her dream and pinches him on the cheek...