Onimusha Tactics begins when demon hordes serving Nobunaga Oda descend on a peaceful province and young warrior Onimaru rushes to defend his home. In the chaos he receives the Oni Gauntlet, a relic of tremendous power that lets him absorb the souls of fallen enemies and use the resulting Genma stones to forge new weapons and armor.
An elder named Sandayu then reveals a truth Onimaru never knew: despite growing up in the quiet province of Iga, he is of the Oni clan — spirited away as a child to keep him safe. Now aware of his lineage and his destiny, Onimaru assembles a makeshift fighting force that includes his sister Ororo and sets out across the war-torn land to avenge his people and put an end to Nobunaga's demonic conquest.