KEPT PRESSING 100-MILLION YEAR BUTTON LIGHT NOVEL SC VOL 01 #1

Allen is training to be a swordsman, but he's just no good at it. After losing a duel with high stakes, he's about to drop out when a mysterious man offers him a chance to get 100 million years' worth of training with the press of a button. But what happens when he presses it over and over?!