RWBY is a webseries set in the world of Remnant where the supernatural abounds and creatures called Grimms exist. The hunters who battle the creatures of Grimm receive their training at academies. At Beacon Academy, Ruby, Weiss, Blake, and Yang make up one of the teams of hunters. Each of the hunters has a unique weapon and ability which helps them in combat. The characters also reference particular fairy tales.
Ruby is the main character as well as the youngest character of the series. Although she is smaller and seems younger in more ways than one, she is also very intelligent and has excellent fighting skills. The fairy tale that corresponds to Blake is Red Riding Hood. For more, please visit Ruby at the RWBY Wiki.