It was always hard to get context and detail on the game from the Japanese sites, but the many videos do a pretty good job. However, some detail always helps, so take this from the press release for now:
Presented with a gorgeous palette of rich colours and a distinctive hand-painted art style, Grand Knights History takes place in the land of Listia, a medieval continent plagued by conflict as the struggle for land and power sees three competing nations in stalemate. For years, the lands of Union, Avalon and Logres have battled one another for supremacy, with the resulting bloodshed reaching epic proportions. With no nation able to gain an advantage the war rages on unabated.
While these three nations vie for continental domination, one captain must choose a nation with which to align himself, then recruit teams of able-bodied soldiers, train them into battle-ready knights and send them to the ever-changing persistent online war campaign. It is up to players to choose an allegiance with one of the three factions, then progress through offline questing and intense 30-hour online skirmishes, all making use of deep, strategic RPG combat and expansive customization. Race, sex, appearance, job class, sub-class and weapon type are all freely alterable for every team member, so no two knights are ever the same; and online functionality allows players to test their knights against others from all corners of the globe without even requiring a constant internet connection.
“Muramasa: The Demon Blade was a huge success story and a pleasure for us to work on,” said Martin Defries, managing director, Rising Star Games. “Vanillaware represents everything good about Japanese games development and I am delighted that Rising Star Games is once again associated with such an esteemed team. We are extremely excited to combine our expertise with such talent on another release in Europe.”