When the delicate balance between worlds begins to unravel, Serenity must journey deeper into the unknown to face the ultimate test of courage and resolve. Joined by her friends and unlikely allies, she races to stabilize ancient Nexus Points while confronting the sinister Akuma no Kage, whose ambition threatens to destroy both the human and yokai realms. With her bond to the artifact growing stronger-and more dangerous-Serenity discovers that saving the worlds may come at a cost she's not ready to pay.

In this thrilling sequel, Serenity and the Yokai's Vow, the lines between light and shadow blur, and the fate of two worlds rests in the hands of one determined girl.