3 years have passed since Avatar Korra ended the Earth Empire’s Invasion of the United Republic under Kuvira’s leadership.

After the event of Harmonic Convergence, there were numbers of people who discovered their newfound power of Airbending.

But that did not happen to Rei, who always wanted to be a bender. A 17-years-old boy immigrant who lived in the Fire Nation with his firebender friend, Yuni.

One day, he saw a fight between four men with a mechanical gloves and a girl with the Earth Kingdom emblem the back of her green clothing.

When he tried to help her, a power within him was suddenly awoken with a help of a strange spirit.

Only the power was not Airbending, but something else . . . .