Maehyeong

Lee Joon lost his parents in an accident and lives alone with his older sister. He meets Sang-Hyeon while working part-time to earn money for college tuition. Sang-Hyeon always has a relaxed attitude, a calm tone that draws attention to his mature atmosphere and is financially perfect. Lee Joon admired Sang-Hyeon, who was different from him, and couldn't help but fall in love at the same time. The two loved each other, but as they began to fight frequently over their older sister, Lee Joon ended up pushing Sang Hyeon away. And one day, Sang-Hyun announced that he was getting married to Lee Joon's older sister.

(Source: Peanutoon, translated)

Note: Includes 1 extra chapter.