Yuma, then only 7 years old, was camping with his parents in Mt. Shishio when Monogelos attacked, but somehow miraculously survived unhurt. This experience led him to pursue the path of kaiju biology research, and despite his traumatic past he has not lost his imagination. As a rookie investigator, Yuma joined SKIP and was assigned to the Hoshimoto City Branch. Not long after, another large-scale kaiju disaster occurs. As Yuma sees the desperate people in front of him, a strong will springs into his mind --- "I want to protect them!" It was at that moment when Yuma hears the voice of Rution, the being of light that he once saw as a child: "You and I are one and the same... Unleash your imagination!" When the mystic light emerging from Yuma's hand embodies his entire body, his power of imagination fuses him with the light and he transforms into Ultraman Arc, the Giant of Light who protects the future! Alongside his precious friends, Yuma gallops towards his everlasting dream!

Everything begins when a mysterious space sage, Sascal, poses this challenge to Yuma. Sascal sets three trials to test Yuma's worthiness as a true hero. Protecting Hoshimoto City as a member of SKIP, building trust with his comrades, and wrestling with the inner conflict over the meaning of defeating kaiju --- all these responsibilities weigh heavily on Yuma ever since he gained the power to transform into an Ultra hero. Now, these very burdens are twisted by Sascal, who manipulates them, launching one test after another.

With rampaging kaiju, evil aliens wreaking havoc, and a warped, alternate dimension where even time itself is distorted, the dark Ultraman Arc, Guil Arc finally emerges. Can Yuma --- Ultraman Arc --- rise above the greatest test of all and protect the future, surpassing even the limits of imagination? Starring: Hiroki Matsumoto, Yuka Murayama, Nobunaga Daichi, Sae Miyazawa, Masaya Kikawada, Hiroshi Tsuchida, Yu Koyanagi