In an extremely hot summer, two 10-year-old male and female protagonists lost their younger brothers at the same time. One suffered from organ failure due to a long-term high fever; the other died from burns due to a fire in a car oil tank. The younger brother who was left in the car was burned and rescue efforts failed. Although the tragedies are different, the ending is the same. The two people who were living happily at the same time were burdened with a sinful secret. The woman knew that her brother was not feeling well, but ignored it; the man left his brother alone in the car and went to play the game console near the supermarket. Due to a mistake, they lost their dearest person this summer. So, when they met in the cemetery, they made an agreement to give each other's secrets to each other, transfer their hatred to each other, and agreed to hate each other forever, never meet again, and live well! They never expected to cross paths, but they got together because of a wonderful encounter. Their friends knew that the same thing had happened to them, and helped them arrange a friendship, and lied that they wanted the hero and heroine to go on a blind date on their behalf, and tried every means to make the other party hate them and break off the engagement. The story begins...