Namjachingureul Josimhae

"I'm your boyfriend... from the future." High school students Da-In Son and Si-Hyun Lee could hardly be called close. One day, Da-In is approached by a man who claims to be Si-Hyun from the future. What’s more, he says they end up dating and he has traveled back in time to stop a murder. As Da-In and “future S-Hhyun'' become more involved, Da-In and “present Si-Hyun”’s friendship also changes. What will become of such entangled relationships? How will the future change? (Source: Manta) Note: Chapter count includes 8 extra chapters.