Decades ago, a being known as the Giant of Light joined together with Shin Hayata of the Science Special Search Party to save Earth from an invasion of terrifying monsters called Kaiju. Now, many years later, those dark days are fading into memory, and the world is at peace. But in the shadows a new threat is growing, a danger that can only be faced by a new kind of hero--a new kind of Ultraman...

The battle against the Star of Darkness in New York City ends in a blinding flash of Spacium rays. While things return to normal for the SSSP, in the aftermath, Adad betrays the Star Cluster Council and flees to Hong Kong. Now, two assassins known as the Leo Brothers have been sent to hunt him down. In this battle of unleashed beasts, there is only victory or death...