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Basically yeonwoo has been in a trauma after he and his parents got into an accident. He overheard the relatives questioning why he's the only one who's uninjured when his parents were in critical condition. They said he's too lucky and he's sucking all their luck that's why their lives are miserable. He took what they said to heart and has been blaming himself.
Also, pretty sure it's one of the relative that sabotaged the car. The relationship between his parents and his grandpa/family wasn't good bcs they got married without the old man's permission. The grandpa wanted his dad to marry another woman for you know, to expand their business.
spoiler me pls what’s the sad backstory?