Ink is an alien encountered by human children on the moon, operating a junk shop with her father, Rubin, a traveling repairman. Her distinctive appearance features arms instead of hair and rosy cheeks, often complemented by a hat. Ink forms a bond with the human child Kōji Harada, united by mutual curiosity. Together with her father, she possesses a rocket ship meticulously assembled from spare parts over an extended period. This rocket proves essential for the children's journey to an interstellar festival, aiding their confrontation of antagonists and resolution of the narrative's central conflicts.