ssehun

Correct

Spoiler**
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Okay I believe if I remember correctly; The system and game ig is actually Seo Hojin’s manifestation of wanting his brother to live a happy life. I don’t actually remember if he had an accident or not since I looked at spoilers for this like a year or two ago. But Hojin knows how soft his brother actually is and adores him and wanted him to be better off. **Okay I went back to the forum and found it for you, Seo Hoyun did die due to overwork and Hojin became a PD like Hoyun eventually managing to create the idol world Hoyun is a part of rn. It was very depressing when Hoyun first found out about it.
If you would like to know more in depth, I suggest going to the NU spoiler forum page 2 and read Ame123’s comment. The answer is in point 3 of the second spoiler tag, you have to open the first tag though to see the second one

spoiler
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Hoyoon did die from the car accident the we saw in the early chapter. Iirc Hojin tried to commit suicide before encountering a mysterious power that can give him a chance (actually many chances) to revive Hoyoon in exchange of his own life force. This idol game that we're currently reading about is actually his latest chance to bring Hoyoon a new life. Hojin actually has witnessed Hoyoon dying multiple times during the various courses of these 'games'....

HOJIN IS AN ANGEL ╥﹏╥

he really is T^T Hoyoon did well raising and protecting him all this time...