The Dungeon of Black Company Vol. 5 (manga)

IT GIVES YOU WINGS!

The key to ultimate power is waiting at the bottom of the dungeon, and Ninomiya Kinji is in a race with a crooked megacorporation to get his hands on it. But there's one small problem--he's totally broke. An unlikely get-rich-quick scheme might provide the answer, as Kinji joins forces with destitute shopkeeper Cindy, and soon, every adventurer in the world will be clamoring for...magic energy drinks?!