"Tomatoman" centers on a post-apocalyptic world where humanity struggles to survive after a catastrophic event has rendered most of the planet uninhabitable. The story unfolds in a barren wasteland where resources are scarce, and survival depends on the cultivation of a mysterious, genetically modified crop known as "Tomatos." These Tomatos are not only a vital food source but also possess unique properties that grant enhanced abilities to those who consume them. However, their cultivation is tightly controlled by a powerful corporation, AgriCorp, which monopolizes the distribution and enforces strict regulations to maintain its dominance.

The protagonist, Kaito, is a young farmer who lives in a small, struggling settlement on the outskirts of the wasteland. After discovering a rare, unaltered Tomato seed, Kaito becomes the target of AgriCorp's enforcers, who seek to eliminate any threat to their control. With the help of a rogue scientist named Dr. Hana, Kaito learns that the unaltered Tomato has the potential to restore the planet's ecosystem, offering hope for a sustainable future. Together, they embark on a journey to protect the seed and uncover the truth behind AgriCorp's sinister agenda.

As Kaito and Dr. Hana travel across the wasteland, they encounter various factions, each with their own motivations and conflicts. Among these are the Free Farmers, a resistance group fighting against AgriCorp's oppression, and the Nomads, a wandering tribe that views the Tomatos as sacred. The narrative explores themes of survival, environmental restoration, and the ethical implications of genetic modification, while also delving into the personal struggles of the characters as they confront their pasts and forge new alliances.

The series balances action, suspense, and emotional depth, with Kaito's growth as a leader and his evolving relationships with Dr. Hana and other key characters driving the story forward. The world-building is detailed, presenting a stark contrast between the desolate wasteland and the lush, vibrant potential of the restored ecosystem. "Tomatoman" ultimately builds toward a climactic confrontation between Kaito's group and AgriCorp, with the fate of humanity and the planet hanging in the balance.