The Demon Sword Master of Excalibur Academy, Vol. 3 (manga)

After a tough battle, Leonis has managed to protect the Seventh Assault Garden from the attack by the Archsage, Arakael. Soon, he gets wind of the Imperial princess's visit to Excalibur Academy and attempts to make her acquaintance...but meanwhile, in the shadows, the fearsome scheme of the "demon sword wielders" is beginning to take shape.