The Black Wolf versus the Wild Tiger!!The girl who suddenly appeared before Yuuto turns out to be none other than Sigrdrífa, the reigning divine empress of the land of Yggdrasil. Equally shocking for Yuuto is the fact that she bears an uncanny, twin-like resemblance to his childhood friend Mitsuki.As she is traveling incognito, Yuuto welcomes her to stay in the Wolf Clan palace for the time being, and he soon learns information from her that may hold the key to his returning home to the modern era. But just as Yuuto's hopes are rising, the Lightning Clan attacks once again, led by the Battle-Hungry Tiger Steinþórr!Yuuto moves to intercept them with a new clever scheme, but...?!