The time is Sengoku.

Japan is fractured into many independent nations entangled in ceaseless war. At the center lies Ashina, a land of sacred earth and ancient mystery. Two decades after Sword Saint Isshin Ashina reclaimed the region in a brutal coup, a new threat emerges from within: The Interior Ministry. Desperate to protect his homeland, Isshins grandson Genichirou turns to forbidden powers. The only hope lies in a kidnapped boy — the Divine Heir — and his silent protector: a loyal shinobi known only as Sekiro.

This is the story of a lord and his retainer — and their quest to restore balance to a nation on the edge.

(Source: Crunchyroll)