Aoba Watase is a normal Japanese first year high school student coming back to school after summer break when a mysterious robot from the future comes after him. He has never seen it before, but its pilot seems to know him and wants him dead. His classmate Hina Yumihara appears in a giant robot of her own. She rescues him and tells him to get inside the cockpit. She defeats the mysterious robot but after Hina explained what happens to Aoba, the mysterious robot wakes up then clings to Hina's mecha, the pilot initiates a self destruction and tells Hina that she's going to die together with Aoba Watase and him. Meanwhile, a time vortex appears in the sky, Hina decides to bring them enter the time vortex. Inside the time vortex she tells Aoba cryptically "You're going to the future now, Dio is waiting," before she disappears. When Aoba wakes up, he finds himself in a strange cockpit alone, thrust into the middle of a furious firefight.
誠應高等学校に通う渡瀬青葉は、明るく友人思いな少年。夏休みも明け、久しぶりに
登校した青葉は、友人とバスケットボールをしているところを謎のロボットに襲われる。
それは、未来からやってきた人型戦闘機・ヴァリアンサーだった。
友人を守るために一人逃げ惑う青葉。
絶体絶命と思われたその時、もう１機のヴァリアンサーが出現。
そのパイロットは、なんとクラスメイトの弓原雛だった！
Aoba Watase es un estudiante normal de primer año de secundaria que regresa a la escuela después de las vacaciones de verano cuando un misterioso robot lo persigue. Nunca lo había visto antes, pero su piloto parece conocerlo y lo quiere muerto.
신학기가 되어 새로 자리배치가 된 교실. 와타세 아오바는 평소 자신에게 왠지 서먹하게 구는 미소녀 귀국자녀, 유미하라 히나와 나란히 앉게 된다. 그러나 이런 그녀에 적응하기도 전에 와타세는 갑자기 전투 로봇의 공격을 받게 되는데...
