Onimusha Tactics takes place in a world in which Genma, the evil creature of the underworld plans to invade the country to establish the Genma Empire. Ordered by their evil lord Nobunaga, the demon warriors begin their attacks on humans. Meanwhile, a young man of Ogre clan named Onimaru was training to attain higher sword skills when he received an urgent message from his master Momochi telling him to come home immediately.