Badminton player Taiki has always admired basketball star Chinatsu from afar. But one spring day, a surprising turn brings them unexpectedly close.

After being suddenly transported to another world, Subaru Natsuki and his new female partner are brutally murdered. However, Subaru awakens to a familiar scene, meeting the same girl again. The day begins to mysteriously repeat itself.

As a prophecy of doom unfolds on the peaceful land of Britannia, a purehearted boy sets out on a journey of discovery — and revenge.

A young man becomes host to a legendary infernal sword and, with the fate of humanity now in his arm, wields its demonic power against his enemies.

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.