"Lost World" is a science fiction manga written and illustrated by Osamu Tezuka, serialized in the late 1940s. The story is set in a universe where Earth faces the threat of destruction due to a rogue planet, Mamango, on a collision course with it. The narrative intertwines the fates of humans, aliens, and genetically engineered beings, exploring themes of survival, morality, and the consequences of scientific ambition.

The plot centers on Dr. Shikishima, a brilliant but morally ambiguous scientist, who conducts experiments to create hybrid life forms. His creations include Kenichi, a human-plant hybrid, and Ayame, a human-animal hybrid. These experiments are part of a larger plan to ensure humanity's survival as Mamango approaches. Meanwhile, a group of aliens from Mamango, led by the enigmatic Commander Bulldog, arrives on Earth with their own agenda. The aliens possess advanced technology and a mysterious connection to Earth's fate.

As the story progresses, tensions rise between humans and the Mamango aliens, with Dr. Shikishima's experiments becoming a focal point of conflict. Kenichi and Ayame struggle with their identities and roles in the impending catastrophe, while human factions vie for control over the alien technology. The narrative delves into the ethical dilemmas of genetic manipulation and the lengths to which individuals will go to preserve their species.

The climax revolves around the impending collision of Mamango with Earth, forcing characters to confront their choices and the potential extinction of humanity. The resolution explores the consequences of their actions, leaving lingering questions about the future of Earth and its inhabitants. "Lost World" is a foundational work in the science fiction genre, blending speculative science with philosophical inquiry and character-driven drama.