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! As the Spirit Sisters continue to be targeted by demons, Ein has no choice but to seek out and defeat their enemies. Once Krushu and May join the party, things get even livelier, and the sisters spend fun, peaceful days together. But only Yuri's guardian Ursula looks gloomy... Can Ein save Ursula from the darkness in her own heart?!