Noblesse

For 820 years he had slumbered with no knowledge of mankind's advancement and scientific progress. The land which he once knew has become an unfamiliar place with new technology, attitudes, and lifestyles. Upon awakening, Cadis Etrama Di Raizel (aka Rai), seeks to familiarize himself with this era. He locates a loyal servant of his, Frankenstein, who is currently the principal of a South Korean High School. Rai decides that this school is the perfect place to help him learn about the modern world, enrolls, and begins associating with a group of good-natured students in order to 'blend in'. But this new world is no safer than the old; and the dignified, bewildered, technologically inept Rai finds himself embroiled in adventures both ridiculous and dangerous.

(Source: Eat Manga)