A Bloody Hero with Bloody Love (Adopted By Reading-Fan_4_4)

A guy wearing a silver and green long coat shows up at Honnoji academy to see some girl with a red streak of hair get clobbered but he steps in and defends her getting the attention of everyone including the head bee queen of the school. Who is this guy? Why is he here? Where did her come from? What surprises await? Why the hell am i asking you all these questions you don't know!? Why does have a black scissors blade? And why is saying Dragon Blood?