6 years after the 2nd defeat of Z-Arc, Yuya Sakaki, alongside the spirits of Yuto, Yugo, and Yuri, are living a good life in Paradise City, when one visit to the library transports our four heroes into another world alongside 3 other people wielding a Sword, a Spear, a Bow, and… a Shield? Can Yuya Sakaki save the world with 3 spirits, a shield, and a slave? Find out now!