In Oda Nobuna no Yabou, high school student Yoshiharu Sagara wakes up in the middle of a Sengoku-period battlefield and is rescued by the legendary Hideyoshi Toyotomi, but only at the cost of the hero's life. With his dying breath, Hideyoshi asks Yoshiharu to become a feudal lord in his place, and the shock deepens when Yoshiharu saves Nobuna Oda, who turns out to be the female counterpart of the famed Oda Nobunaga. Before long, he realizes he has been dropped into an alternate reality where most of Japan's historical warlords are cute girls.
Determined to keep history from drifting even further and to find a way back home, Yoshiharu becomes one of Nobuna's retainers and helps her pursue a conquest of Japan. As Nobuna launches her campaign, he uses the knowledge he gained from the video game "Nobunaga's Ambition" to anticipate future events and change the course of battle. With that unlikely advantage, Yoshiharu aids the Oda clan's beautiful generals and hopes to help his new lord fulfill her dream and win the hearts of women everywhere.