'해당 계정은 게임 입장이 제한 된 상태입니다.'
The account states that this game entry restrictions.
Er...I'm not entirely sure what that's about. I'll ask Kanra to look at this and try to help you.
You might get surprised by the maximum retardedness of Naddic for this one, but be prepared.
First of all, I need to tell you that Closers is NOT operable properly on Windows 10. That is one risk that you probably took when you were upgrading to it.
When someone with Windows 10 asked about Closers not being operable properly on it, the devs simply said that the recommended operating system was Windows 7 for Closers, therefore not really providing any support for Windows 10.
So I don't know what to tell you. What is true is that Closers just isn't going to run in Windows 10 smoothly, and the devs aren't going to provide fixes for it anytime soon. Only thing I can tell you is to try to re-connect from the previous operating system and see if it still says that message :/
Guess I'll defect to Closers JP and wait till Levia comes out :\
If you'd like me to help send a ticket to Naddic for ClosersKR, feel free to PM me in Discord chat. I'd be glad to help.