In the beginning of the movie, 20 years ago, on the moon, the 4 Ultra brothers, Ultraman, Seven, Jack, and Ace were fighting a deadly foe known as Yapool, a monster that was several times their size. As they fought, Yapool had a clear advantage and used his several claws to grasp the brothers, although, they managed to clear from the claws through there powers and used a combined Specium Ray to no avail. The monster then flies off to Earth to dodge the attack and the brothers follow. The brothers were barely able to defeat Yapool but the monster still needed to be sealed. However, to seal Yapool away they were forced to give up the ability to transform, and took up jobs to be in the area of Kobe in case the monster ever returned.
ウルトラマンメビウスが地球防衛に就く20年前のこと。異次元人ヤプールの怨念の集結した究極超獣Uキラーザウルスの地球侵攻を阻止するため、ウルトラ4兄弟は月面で激しい戦いを展開。苦闘の末にUキラーザウルスを神戸港沖に沈め、ヤプールの怨念も封印した。そして現在…4兄弟は地球人の姿で生活をし、封印を監視し続けていた。神戸港における異変を察知し、調査のため現地へ赴いたウルトラマンメビウス＝ヒビノ・ミライ。地球征服をたくらむ宇宙人連合のテンペラー星人から戦いを挑まれてしまい……。
