In the world of Gift, the planet's bowels conceal a highly sought-after crystalline substance called Giftium. Sougo Amagi, a young boy on Gift, inherited his interest in Giftium from his mother, a researcher. Living in Garden Indigo, a small and prosperous mining town, Sougo has many opportunities to forage and collect rare crystals found only there. However, the most exciting treasure Sougo discovers is not a crystal, but a person. After getting pulled into a school quarrel, he plummets into the deep caverns of an old mine. There, in the abysmal depths of the earth, Felia—an enigmatic girl with red eyes and blue hair—emerges from a large crystal. Through this strange first encounter, bonds of friendship form between Felia and Sougo. But Felia is being pursued by a secret organization that aims to use her powers for their own benefit, and Sougo and his friends must help her, all while discovering the true nature of this girl from the crystal.