ユナの１８歳の誕生日がやってきた！でもそんなおめでたい日なのに、石化闇魔獣ガーゴルゴンが超古代から蘇ってしまう。
怪獣が迫る中現れた謎の黄色い戦闘機、ついに語られるシズマ会長の過去、そしてユナの出生に隠された秘密とは一体！？
It's Yuna's 18th birthday! But there's no time to celebrate, as Gargorgon, the Petrification Dark Evil Monster, is resurrected from the depths of antiquity. As the monster closes in, a mysterious yellow fighter jet appears. And at long last, President Shizuma's past, and the hidden secret behind Yuna's birth are finally revealed!
