Seiken Gakuin no Makentsukai
English name: The Demon Sword Master of Excalibur Academy
Genres: Action, Fantasy
Type: TV, Episodes: 
Aired: Not available
Studio: Passione
Source: Light novel
Rating: PG-13 - Teens 13 or older
Synopsis:
Battles for ancient kingdoms are nothing compared to the battles of a classroom!

Awakening from magical stasis after a thousand years, the Dark Lord Leonis suddenly finds himself in the body of a ten-year-old boy! He quickly meets Riselia, a girl confronting the Voids, creatures that have nearly exterminated humanity. Determined to uncover the mysteries of this strange new era, Leonis enrolls in Excalibur Academy, a school that trains students to fight back against these enigmatic monsters. Could the Voids hold some connection to Leonis's past? 

(Source: Yen Press)