The Demon Sword Master of Excalibur Academy, Vol. 2 (light novel‪)‬

A MYSTERIOUS HIJACK ON THE HIGH SEAS!
When a princess visits the Seventh Assault Garden, Leonis believes it’s a chance to expand his influence as a Dark Lord. Unfortunately, the celebrations are cut short by a Void attack. Things get only more treacherous when a rebel group seizes control of the princess’s ship! Leonis and the rest of his squad plan to retake the vessel, but there appears to be more at work than a simple insurrection. And why does Regina seem to know so much about the princess?