The "Strong Armor" is a super-biological weapon left by aliens who came to Earth tens of thousands of years ago. An ordinary high school student, Akira Fukamachi, accidentally got Kaba, and his senior from the same school, Jawman Makishima, got another set. As a result, they became the targets of the secret organization Knoss. After that, the two will face the pursuit of the beast soldiers sent by the mysterious organization Knoss. Gradually, the secrets related to the origin and future of mankind become clear...