Osamu, a cereal salesman from Japan living in the US with his close friend Jay Gibson, experiences a life-altering event during a nighttime drive. He and Jay encounter a military barricade near crashed capsules under attack by vampiric entities. Taking cover, Osamu discovers a cryogenic container holding Kimera, an androgynous green-haired alien. The chime of a silver bell Osamu wears awakens Kimera, who kisses him through the glass, forging an immediate, profound connection.

Detained at a nearby Air Force base, Osamu feels Kimera's psychic call. Compelled to find them, he uses a stolen security card, aided by Jay, to infiltrate restricted areas. He locates Kimera in a laboratory greenhouse and releases them, culminating in another passionate kiss. This act alerts hostile alien pursuers, thrusting Osamu into conflict.

After an explosion separates them, Osamu dreams of Kimera's past: their bond with the vampire Kianu, their refusal to become a reproductive "Mother" for their dying species, and the trauma associated with that role. This vision deepens Osamu's empathy and resolve. Reuniting, Kimera initiates intimacy, mistaking Osamu for Kianu, a misconception Osamu gently corrects. Their moment is interrupted by the alien Ginzu, who captures Kimera to forcibly connect them to a breeding system.

During the battle between Ginzu and Kianu, a mortally wounded Kianu teleports Osamu to Kimera. Kianu implores Osamu to kill Kimera to prevent Earth's destruction by their potential offspring. Faced with this tragic choice, Osamu hesitates and cannot kill Kimera. He later appears fleeing with Kimera into a desert landscape, consciously choosing companionship and love despite acknowledging the apocalyptic risk their union may pose to humanity. His final words express commitment to hope and a future with Kimera, accepting the uncertainty of their path.