Fate/Extella Link - VITA

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.