Reincarnated into a magical world full of adventure, a formerly aimless and unemployed man decides to live his new life to the fullest.

When sinister forces threaten the peace of Britannia, a young prince embarks on a perilous journey to save his loved ones and discover his true powers.

The theft of the Greater Grail from Fuyuki City leads to a splintered timeline in which the Great Holy Grail War is waged on an unprecedented scale.