Apreté el botón durante cien millón de años y antes de darme cuenta, fui el más fuerte

Allen is a boy who is despised as a failed swordsman. One day, desperate for a duel with an elite swordsman who bets on leaving Kenjutsu Academy, a mysterious hermit asks him if he will press the "100 million year button". Can the mysterious object really help him train for 100 million years?