The Unaware Sword Saint Who Trained for 100 Million Years: Overwhelming Another World with the All-Purpose Divine Artifact Mocked as a Mere Stick and the “Sword Demon” Persona Born from Extreme Training

Synopsis

The only reason he is the strongest is... effort!! Ichitaro, a high school boy, has a personality that causes him to get completely absorbed in a single thing. One day, his entire class is transported to another world as heroes. The hero rank assigned to him at his destination is the worst. Deemed a useless existence, Ichitaro is locked away in a prison where time has stopped. What he did there... was training for 100 million years. By the time he left the prison, he had mastered each and every swordsmanship style, becoming the strongest hero!!