Houseki no Kuni

In a ruined future, Gems—crystalline beings—live under threat from the Lunarians, who attack to destroy them for decorative purposes. Each Gem is given a role in the defense, but Phos, a young and fragile Gem, is assigned to write an encyclopedia due to their weak state. While reluctant, Phos meets Cinnabar, a Gem whose corrosive nature limits them to night patrols on a remote island. Observing Cinnabar’s unhappiness, Phos seeks a way for both to find purpose beyond their assigned tasks. The story follows Phos’s attempts to contribute meaningfully and safeguard their Gem companions.