The Boy Who Ruled the Monsters: Volume 4

"With the spectacle of angels and dragons of the Oratorio Tangram over and the human world now in his hands, Sol decides to take a moment to enjoy some time off on an island resort that was gifted to him to curry favor. It’s an opportunity to lay off the theatrics for a while and simply enjoy being a group of teenagers hitting the beach. At least, that is until Sol’s group receives word that the Floating Continent is making a reappearance, bringing with it Alshunna, the Vacant Demon Lord, who was bound to it. A showdown between two mythical monsters from a thousand years ago finally goes down in volume four of this relentless epic of the greatest supporter and his party. It’s sure to reshape their very world!"

[From J-Novel Club]