Those who actually watch the movie of K Project must have seen this dude.
Yukari, The Green King.
Yukari is pretty intelligent and he have this sort of bond with Yatogami.
Yukari is pretty badass and he pretty much beat the crap out of Yatogami.
Yukari is also sensible. His blade and his mindset at fighting can turn the game around quickly.
to be honest, don't mess with the Green King.
He have his own army and an special girl on his side.
(Not Spoiling it.)
For those K Project lovers, YES! He'll be in Season 2 of K project.