Kenichi Kohiruimaki begins as a middle school student deeply engrossed in conspiracy theories and online subcultures, actively debating extraterrestrial phenomena on internet forums. He enters a romantic relationship with classmate Kiho Kurihara, but conflicting beliefs about alien invaders cause their separation.

Kiho's death in an incident involving wreckage from a destroyed alien spacecraft profoundly alters Kenichi. Her loss shifts his theoretical fascination into militant action against the invaders. Radicalized, he abandons his education to establish the paramilitary Youth United Front, dedicated to eradicating extraterrestrial forces.

As hostilities intensify, Kenichi's faction evolves into the formidable political-military entity New Japan Harmony. Leading this group, he engineers a successful coup that overthrows Ogino's government, seizing de facto control of Japan. His manifesto demands aggressive military strikes against the aliens, directly shaping state policy and escalating societal unrest. One official, Miura Tarou, commits suicide after reading the manifesto and observing the ensuing turmoil.

Kenichi's impact spans timelines. In an alternate reality stemming from his post-Kiho radicalization, the Youth United Front's ascension occurs. This timeline dissolves when Nobuo Koyama travels back to prevent the alien arrival, creating a new reality where Kenichi avoids the trauma that forged his militant path.

The ONA adaptation depicts further repercussions of Kenichi's rule: New Japan Harmony soldiers execute refugees Kimika Ando and Hako Shimoda to eliminate witnesses during a clash involving Nobuo Koyama. This portrayal differs from the manga, where both refugees face execution during detainment procedures.