Samejima  

Marionette King, 鮫島; マリオネット・キング

The main antagonist of the manga Ichitakas high school is a former senior named Marionette King. He repeatedly tries to take advantage of Iori with different schemes but is always thwarted by Ichitaka. After failing in his first attempt, he gets expelled from school. Following that, he becomes addicted to drugs and on the brink of insanity. In the final story arc, he plays a significant role. His internet handle is Marionette King, and although his real name isn't mentioned in the manga, it's revealed as Samejima in an OVA called Is Pure.