When I Loved You Vol. 1 (novel) - When I Loved You, #1

An unyielding woman. A scheming man. An unfulfilled promise.  Yiyoung Yoon's life has always been an uphill battle. Although she had a loving family, she became burdened with endless bills when her mother fell ill and her father lost his job. This made her realize at a young age that she must fight tooth and nail for success. Her hard work appears to pay off when she earns a full-ride scholarship to an elite private elementary school.
She enters it with high hopes and big dreams of supporting her family and ensuring their future, only to find herself swimming with sharks eager to make her their prey. In her attempts to navigate this difficult environment, Yiyoung becomes entangled in the life of her deskmate, Muyeol Cha, a loner who seems untouchable due to his high social status. The more they spend time together, Yiyoung comes to understand that looks can be deceiving.
She and Muyeol become close, but eventually, life separates them. Despite their diverging paths, fate binds them together through a promise Yiyoung makes. Thirteen years later, he's back to reap that promise. Time passes and people change, but may they find beauty in life all the same.