The value of your life?

Who really knows how much a life is worth but when Shiro tried to sell his to Dark the demon. He has been tasked to find out and to amuse the demon at the same time... but surely this is going to be a one sided massacre? well that is why the demon gave Shiro two guns, he forgot to mention that they take HP to use! well now I wonder how long can Shiro last with just a pair of guns and his wits... …