In the distant future, a new life form known as the Gems has come into being. The twenty-eight Gems must defend themselves against the Lunarians, moon people who attack them and turn their shattered bodies into ornaments. Every Gem is given a role, such as fighter or medic. Phos, the youngest, longs to battle the Lunarians but is left without a duty until Kongo, who oversees the Gems, asks her to compile an encyclopedia of natural history. This single-episode ONA is a promotional video posted on YouTube to mark the release of the manga's first volume, pairing action and fantasy with science fiction.