In a world where magical Book Companions are cherished guides, Yushina and her friends, Sakano and Mashi, thought they knew the full power of their bond. With their companions—Yuki, Blaze, and Luxis—they’ve explored far and wide. But when they find a village where people’s companions are mysteriously stolen, their journey takes a dark turn.

An ancient figure, the Keeper of Shadows, has begun capturing Book Companions, severing bonds and drawing on their power. Determined to rescue the lost companions, Yushina and her friends venture into the Keeper’s ominous domain. As they gather allies and press forward, they uncover a sinister plan that threatens the balance of light and dark.

With friendship and fierce determination, they prepare for a battle that will test everything they know about magic, loyalty, and courage. Will they reunite the lost companions and restore balance, or will the Keeper’s shadow consume them all?