there is a race of "nobles" in the world (sorta like vampires- but not vampires) that protect the humans from interference etc.
Raizel - "main" protagonist is "The Noblesse" who vanised 820ish years ago- he is in a coffin underwater- it gets pulled to the surface, then the people who get it get killed, then he wakes up in a strange room sees kids going to school and follows them, ends up in a high school as a new student.
the High School principal is Frankenstein- a human who has powers, who is Raizel's servant.
raizel is of the race of Nobles, who live on a remote island- he is like the executioner of the nobles/last resort -you go bad, he goes and kills you, extremely powerful.
there is "the organization" which is modified humans to have powers (vampires etc) and they tried to get the noblesse- but failed, but one of the students (naturally) saw the people get killed and they try to remove the witnesses...yada yada...
fights ensue where the organization tries to kill the students, frank and raziel (and other nobles eventually) interfere and kill the organization's peeps, powerups ensue, more allies come on, more villians, etc.
its pretty good