The Demon Sword Master of Excalibur Academy, Vol. 8 (manga)

As Leonis is showing Veira around the Seventh Assault Garden, they are suddenly attacked by Muselle, the foe Leonis previously defeated, who should have lost the power of his holy sword. Meanwhile, Elfiné finds out about the Demon Sword Project—a plan to evolve Holy Swords secretly being carried out in the Academy!