"Global Garden" is a science fiction manga that explores themes of environmental collapse, human resilience, and the search for hope in a dystopian future. The narrative is set in a world where Earth's ecosystems have been devastated by climate change, leaving much of the planet uninhabitable. Humanity survives in isolated, domed cities called "Gardens," which are controlled by a powerful corporation known as Eden. These Gardens are designed to replicate Earth's lost environments, but they are reserved for the elite, while the majority of the population struggles to survive in the harsh wastelands outside.

The protagonist, a young woman named Aoi, lives in one of these wastelands, scavenging for resources to sustain her community. Aoi's life takes a dramatic turn when she encounters a mysterious boy named Kaede, who claims to have come from a hidden, thriving ecosystem known as the "Global Garden." Kaede's arrival sparks a journey as Aoi becomes determined to find this mythical place, believing it could offer salvation for humanity. Along the way, they face numerous challenges, including Eden's enforcers, who seek to maintain control over the remaining resources and suppress any hope of a better future.

As the story progresses, Aoi and Kaede uncover the truth about Eden's manipulation of the Gardens and the corporation's role in perpetuating the environmental crisis. They also encounter other survivors and rebels who share their goal of restoring balance to the planet. The narrative delves into the complexities of human ambition, the consequences of technological advancement, and the enduring connection between humanity and nature. Through Aoi's journey, the manga examines the possibility of redemption and the resilience of the human spirit in the face of overwhelming adversity.