oh so it's probably link to their universe
because in their webtoon, the girls adventure outside the dome, when it's suppose to be forbidden
I didn’t think of that.. hmm maybe.. I’ve stopped Crimson heart awhile back so it didn’t even occur to me both might be related.. good call..
I’m still confused the part where Sakura broke the other girls’ linked hand.. what does it mean?
Kpop is actually pretty limited, and if 

I may have exaggerated a bit, but there is definitely a reference to the limitations in kpop or the limitations of society and everything that is considered taboo around them.