Fate/Chaos Theory

Chaos Theory: Just one variable can spark an endless array of possibilities. What is the average man to do when he suddenly gets transmigrated into a different world without warning? Even better when that said world is Fate and the entirety of Human History has been wiped out and you are apparently the only person that can save humanity? Now equipped with a System telling you to seduce historical and mythical figures in the form of heroic spirits to gain power to save humanity what can a man to do? His best apparently Note: I do not own the cover now do I have any claim over it