Hitomi Landsknecht captains the Guardswomen, a paramilitary force protecting humanity's final settlement in a male-extinct, post-apocalyptic Tokyo. She possesses gray hair cut to her neck, wears an eyepatch, and dons a standard uniform featuring military attire, a cape, and combat gear. She wields a large gun and a sword as her primary weapons.

As the protagonist, Hitomi experiences a fragmented consciousness, intermittently sharing mental space with Hitomi Aida, a woman from 1986 recovering from a truck accident. This connection results in disjointed memories and sensory exchanges between the two women. Hitomi Landsknecht has reportedly not slept for three years preceding the main events.

Her mission involves defending the last humans against bioterrorism and rival factions. Initially loyal to Guardswomen Commander Julia, who promotes the experimental ICE technology for reproduction, Hitomi later uncovers ICE's true nature: a terraforming superweapon controlled by the antagonistic Kisaragi faction. This discovery shifts her goal to preventing the weapon's activation. Her protective bond with Yuki, the adopted daughter of the Kisaragi leader, becomes significant. Yuki expresses overt romantic feelings, sparking violent jealousy in others like Satsuki. Hitomi's decisions are often influenced by her desire to shield Yuki.

The narrative concludes with Hitomi sacrificing herself to stop the ICE superweapon. Simultaneously, in 1986, Hitomi Aida awakens in her original timeline and is revealed to be pregnant, creating a thematic loop concerning reproduction and survival.