From Comicloud:

In the 15th century, Japan was thrown into chaos by the military commanders known as the "Sengoku Daimyo" of the Warring States (daimyo = samurai leader), who struggled constantly for territory and power.

Suddenly, like a comet in the sky, a commander with strength and wisdom beyond human understanding appeared and began to unify the country - Nobunaga Oda. But Nobunaga was forced into a terrible situation by the betrayal of his trusted confidant and subordinate, Mitsuhide Akechi.

In reality, behind Mitsuhide's betrayal was an Oni working to stifle Nobunaga's ambitions. What is this Oni planning now!? And who is the girl named Ran, who has chosen to fight this Oni!? The battle against the Oni, which transcends space and time, begins here.