4화: 히노키 사이와 위험한 주말 이후, 아오노 케이타는 학교 생활과 이상한 실종 사건들을 헤쳐 나간다.

4

The day Keita Aono was reunited with an old friend was also the day that his life would be changed forever. With Hinoki Sai by his side, he's piloted a robot and fought with rampaging monsters, nearly dying in a plane crash along the way. And she's only been back in his life for a weekend. Keita's never been much of a student, but school suddenly seems like the safest place to be right now. Things are apparently back to normal. He wipes out on his scooter and all the girls are ignoring him. Unfortunately, Hinoki is one of them. Though confused and insulted by her behavior, it's not long before he's deep in nerdy conversation with Ushii, his friend from homeroom. Though initially they talk about planes, their discussion turns serious when Ushii informs Keita that several students have vanished without a trace. Have the weird occurrences from the weekend spilled over into Keita's school as well? Maybe, but Keita has other things on his mind, like memorizing the Kakuseijin operations manual and tracking down Hinoki to ask her why she ignored him before class. Meanwhile, Hinoki has her own problems. Asked by a teacher to get some paper from the supply closet in the school basement, Hinoki instead finds a man wearing a welder's mask and armed with a blowtorch heading her way. (Source: GaoGaiGar-Betterman Wiki)