Heugyeoksa Eogein

Yu-Mi, 28, spent her school years as a lonely and depressing loner, with zero luck and no blessings. She's overcome her childhood, a dark memory, and now lives each day happily. Leaving behind those perfect days, she time-slips back to her most unfortunate past?! Conflicted between the last love she left behind in the future and the first love she's forgotten from the past!

(Source: Naver, translated)

Note: Includes one extra chapter.