Janitor Isekai

Plunging into a new world! The mightiest demon lord in history is marching on Protagnia. To stop him and his expansive army, the people of Protagnia resort to summoning the greatest kendo master the modern world has to offer. What they got was his janitor. Armed with his filthy mop, and zero sword training, Brigham will take the place of his former sensei and play the role of hero. How hard could it be to defeat a demon lord? Especially if he gets some awesome new fantasy powers. ...He does get new powers, right?