When the Agent of Spring, Hinagiku Kayo, is abducted, spring itself vanishes—plunging the world into unending winter. Refusing to give up, her devoted guard, Sakura Himedaka, searches for her for years. When Hinagiku suddenly returns, the two set out to restore the lost season, face the past that tore them apart, and reclaim the warmth they refuse to lose again.

In a Holy Grail War, Mages (Masters) and their Heroic Spirits (Servants) fight for the control of the Holy Grail—an omnipotent wish-granting device said to fulfill any desire. Years have passed since the end of the Fifth Holy Grail War in Japan. Now, signs portend the emergence of a new Holy Grail in the western American city of Snowfield. Sure enough, Masters and Servants begin to gather... A missing Servant class... Impossible Servant summonings... A nation shrouded in secrecy... And a city created as a battleground. In the face of such irregularities, the Holy Grail War is twisted and driven into the depth of madness. Let the curtain rise on a masquerade of humans and heroes, made to dance upon the stage of a false Holy Grail.