Strongest Sage with the Weakest Crest 15

In this manga adaptation of the popular light novel series, the world's strongest sage will stop at nothing to get stronger...not even reincarnation ONE BOY WILL STOP AT NOTHING TO BE THE WORLD'S STRONGEST...NOT EVEN PERFORMING IN PUBLIC Matthias makes a shocking discovery while investigating the imperial waterworks. Grevil, a wise king from ancient times--and an old friend of Matty's--is somehow alive and working with demons Grevil gives Matthias and his party three months to prepare for a battle to decide the fate of humanity. After extensive training in a dungeon, Matthias and his party decide to confront Grevil, who greets them with a grand public spectacle?