Yeesa Cheung, born on a leap day, believes her birthday is squeezed between 28 February and 1 March in common years. When she celebrates her birthday in 2017, she unexpectedly travels to 29 February 2020 in Sapporo. There she is greeted by two strangers, Ryan Ma and Yu Ka-chung, and finds her future self killed in a traffic accident. After she returns to 2017, only one second has passed, but the three have now to work together to circumvent their common destiny.