Miwa

Miwa is an student of Ishiyama that calls himself Queen and considers himself the fairest of all the school.
He despises Aoi and wants to defeat her, mainly because she has the title of Queen Kunieda.

He treats the MK5 as his underlings, and beats the acting leader, Ikari, when they call Aoi Queen. The MK5 seem to be afraid of him, so that must imply he`s stronger than the five of them together. It`s quite hard to tell, because they are small fries, and Oga did beat him effortlessly quite early in the story.