Since birth, Yeon had a red string on his little finger connecting him to the person he considered his destiny and you were that person. When he met you, he liked you and wanted to live with you for the rest of his life, but you didn't. Even though they always went to school and played together, you dated many people and only saw him as a younger brother. Gradually, he hated the fact that he was connected to you by a fateful string, so he wanted to find a way to cut the string. If he wanted to cut the string, he had to do a mission, but those missions were all about bonding, so sometimes he wondered if this was really a mission to cut the string or to bond it even more. There was a mission that the two of them had to make love, because you also wanted to cut the string so you did it with him and almost every day. Not only did he not want to cut the string anymore but he loved you even more but you didn't feel that way, the day he went to school he met a female senior who he had saved from a pervert the day before. That female friend wanted to invite him out to eat but he refused so the two of them went to a convenience store to chat, unexpectedly you saw that female friend smiling at him and even touching his hand. He also kept quiet and didn't say anything but he felt the string tighten, looked to the left and saw you. Your expression made him think to himself

"What's with that expression? Senior...jealous, hmm?"