It's a crossover set after the Unlimited Blade Works route. It follows Shirou when he receives a mysterious phone call which transports him into the Digital World where there's a Civil War going on with 4 allied armies, The Virus Busters, Nature Spirits, Dragon's Roar and Jungle Troopers fighting against the Dark Masters and their armies, The Deep Savers, Wind Guardians, Metal Empire and Nightmare Soldiers. The version of the Digital World in the story is a combination of it's portrayals in Digimon Survive and Digimon Tamers in that it's a bizarre reflection of our world that has species of flora and fauna that are recognizable from the physical world, but plants grow out of season, junk data bounces around like tumbleweeds, items and machinery found in ruins can still work as intended somehow and there are other unique flora and fauna that are native to the Digital World. There are also pocket dimensions that exist between the Digital World and the World Wide Web which suit the digimon who live there and can be entered at certain points.