wait does this mean joonghyuk is a ruler as well?...he isnt right...?

Yes, he become a ruler

wHA...wAIT SO UH....does he need to kill dokja...?

nope















*SPOILER*
if i remember there should be 4-5 kings left after this with that including both YJH and KDJ

Yes, That's what the system Says, you need to Kill many ruler as possible and steal their flags to become The Ruler King.

i mean yeah