Above the ruined earth lies the realm of SE.RA.PH, a virtual world inside a lunar supercomputer. In this last refuge for humanity, powerful Servants — sentient, digital recreations of famous figures from Earth’s lore and history — battle rogue programs (and each other) to establish dominance and enforce their kind of peace.
But peace may never come again, now that a new threat has arrived to wage apocalyptic war. Standing against the destruction is the hero Charlemagne, a dashing young knight with a hint of sadness behind his bright smile. Join Charlemagne and his comrades — the bumbling paladin Astolfo, the flamboyant Emperor Nero, the mischievous fox spirit Tamamo no Mae, the cynical rogue Robin Hood, and many others — as they rush across the battlefield in the name of humanity.