A tamer is a profession that allows one to tame magical creatures and use them as familiars. This is the profession of the protagonist, Kohaku. However, Kohaku cannot tame ordinary magical creatures. Because of this, he is labeled as "incompetent" and is turned away by every guild. But he possesses a unique constitution that allows him to tame only a certain type of magical creature—the Phantasma, a powerful but rare and elusive species. He is the owner of a "sacred soul" loved by the Phantasma. After being rejected by all the guilds in the Turcolize Kingdom, Kohaku decides to move to another country. Upon learning of this, the Phantasma who had gathered in the Turcolize Kingdom also decide to move with Kohaku. Thousands of Phantasma, revered as gods, who had aided heroes, and who had protected the kingdom, leave Turcolize Kingdom en masse, causing its economy and military strength to plummet. They don't know that this is a tragedy caused by one boy's relocation, the consequence of rejecting him. They are walking the path to ruin... at this time, no one knew.