The "Noblesse" Cadis Etrama di Raizel, popularly known as "Rai," is enrolled in Ye Ran High School by his servant Frankenstein in order to keep Rai concealed from the Union, a mystery group out for Rai's blood. Rai begins his life as a student, becoming acquainted with his peers and the daily routines of humans. However, Rai's new existence is far from calm, and he is soon obliged to rescue his new companions from the hands of the Union, who had abducted them. Meanwhile, M-21, a Union agent who went rogue during Rai's rescue mission, joins the Ye Ran High School security team after being approached by the school's director, who happens to be none other than Frankenstein himself. M-21 appears to be a prim and proper gentleman.