In the distant future, a new immortal and genderless life form called Gems populate the Earth. The 28 Gems must fight against the Lunarians who attack them regularly to abduct them and turn them into decorations. Each Gem is assigned a role such as fighter or medic. Phosphophyllite, the youngest Gem has not been given an assignment due to a lack of skill. One day the master of Gems, Kongou, assigns them the task of creating an encyclopedia of natural history.