Ein, an appraiser whose only power is the ability to appraise items, received horrible treatment from his other party members, and his days were filled with despair. But after he happened to fall into a hidden dungeon and met Yuri, a World Tree Spirit, and her guardian Ursula, Ein's destiny changed completely. With the power of his new spirit eye, Ein quickly goes from the weakest of all to the strongest! After defeating the demon Shadow, Ein has become the new lord of Rayshik domain. But there's no time to rest after his victory, as new demons show up trying to kill him! On top of that, Echidna appears in the World Tree hall to attack Ursula and imprison Yuri within the tree. Can Ein and Ursula work together as guardians to save Yuri?!!