This is probably the 1st series where I am not upset that they've changes a few things from the original manhwa.…
Taking a red flag jay and turning him into a green flag is annoying There are many green flag manwha they could have adapted if they wanted a green flag so bad Jay in the manwha still cared for sun even while being a red flag, he still wanted sun to stay with him He still tried to get him not to kill himself.
They lost a lot of the plot with the unneeded changes they are doing to everyone's personality
I just don't get their debt things ....- So ... Sun "owes" Jay for one third of cigarette and the help…
Sun wants to get revenge on Sunny. Sun needs someone powerful to back him up. That's Arthur, Jay is the only person sun knows who can get him to author. Jay implies he needs to pay with his body for help. Sun agrees to pay both jay and author in kind.
Sun is angry jay didn't tell him he was Arthur and wants payment. Jay doesn't mind because he had already agreed to help sun in his revenge plot against sunny in exchange for Sun's body.
They are still on the original plot. The cigarette debt is just a way jay needed to get sun and sun was just upset.
K-Drama 
There are many green flag manwha they could have adapted if they wanted a green flag so bad
Jay in the manwha still cared for sun even while being a red flag, he still wanted sun to stay with him
He still tried to get him not to kill himself.
They lost a lot of the plot with the unneeded changes they are doing to everyone's personality
Sun is angry jay didn't tell him he was Arthur and wants payment. Jay doesn't mind because he had already agreed to help sun in his revenge plot against sunny in exchange for Sun's body.
They are still on the original plot. The cigarette debt is just a way jay needed to get sun and sun was just upset.
these are my favorite tags. Let me dive deep in 🤭😏 at least I have 3 episodes to watch