The symptoms of the "First Love" affliction are as follows: 1) It typically affects adolescents, 2) Being attracted to other people is commonplace, and 3) A heart-shaped scar is present on the patient's body. Haejin discovers that all her classmates have experienced their first loves, except for her. However, at 24 years old, she encounters two potential love interests. The question remains, which of them will be her first love? This series can be found on the original webtoon platform as well as through official translations.