The plot is set in a fantasy world populated by humans, Dragonoids, and Monsters. The three races coexist relatively peacefully. Drops, which are spherical objects that emerge from the planet and can be used to power up the Monsters, are also present. Humans and Dragonoids with the ability to see the Drops, where monsters form bonds, can take on the role of Dragon Callers. The planet is currently experiencing Drop Impacts, which occur when a large number of Drops are suddenly generated in a single area (and can spread), affecting the lands and driving the Monsters insane. In fact, one of the primary responsibilities of Dragon Callers is to settle Drop Impacts by balancing Drop distribution. Ace, the son of King (a powerful Dragon Caller who goes missing at the start of the series), and Rena, who aspires to be a Dragon Caller like his father, is the protagonist of the story. His journey begins when he begins to see the Drops and discovers an egg of a Tamadra, a nearly extinct species, and he moves to Dragoza, a region formerly inhabited only by Dragonoids but now occupied by a large number of Dragon Callers. As the series progresses, he befriends Charo and Tiger, as well as many other Dragon Callers, while honing his skills and knowledge. The Ancients, a mix of Dragonoids and Humans, are the rulers of Dragoza's six regions. There's also Lance, a Dragonoid and a powerful Dragon Caller who frequently encounters Ace (though not as an antagonist) and believes that the Dragonoids will save the planet. The series focuses on the causes of Drop Impacts, with Ace, his friends, and others attempting to solve the mystery and save the planet. Meanwhile, they must contend with Dragonoids in Dragoza, who believe that their race should be the only ones in Dragoza, the only ones to be Dragon Callers, and the only ones capable of saving the planet.