Ichioku-nen Button o Renda Shita Ore wa, Kizuitara Saikyou ni Natteita follows Allen, a scorned student who gains immense power by using a magical button to train for a billion years. The manga adaptation features intense action as Allen surprises others with his skills.
You can find more information and character details on the Failed Swordsman Wiki , or browse community discussions on Reddit . Ichioku-nen Button o Renda Shita Ore wa, Kizuitara