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This is a world where humans and Mechanimals coexist! Kai, a fifth-grade boy in elementary school, is a normal boy who is not good at Mechanimal battles and has no special skills. One day, Kai happens to be taming the mystical Legend Mechanimal, Evan. There's something special happening when not only Evan but also the Legend Mechanimals... Kai is making friends with many tamers and taming more Mechanimals. The exciting battle of Mechanimals and tamers begins!