The narrative begins in a familiar suburban neighborhood where Nobita, desperate to avoid the strict discipline of his mother, seeks Doraemon’s futuristic gadget assistance to bypass a severe scolding for receiving another failing grade on a school test. During his search for a lost sapling in a nearby dumping ground, Nobita stumbles upon a peculiar, miniature plant sprout struggling for survival amidst the urban waste. Feeling a profound, immediate kinship with the fragile seedling, he decides to defy the harsh reality of its environment and rescue it. Utilizing Doraemon’s miraculous plant-growing liquid, Nobita successfully revives the tiny organism, naming it Kibo.As the days unfold, Kibo grows rapidly, developing advanced mobility,
high intelligence, and a deep, emotional attachment to Nobita. Despite the family's initial resistance to keeping a magical mutated plant indoors, Kibo becomes an integral, beloved member of the household. However, the tranquility is abruptly shattered when a bizarre, supernatural cosmic storm sweeps through the town, tearing the fabric of reality and abruptly pulling Nobita, Doraemon, and their loyal friends Shizuka, Gian, and Suneo—alongside Kibo—away from Earth. They are transported directly into the heart of the Green Planet, a hidden, thriving dimension governed entirely by an authoritarian extraterrestrial plant civilization.Upon arrival, the group quickly discovers that the planet’s ruling elite, led by the stern and disillusioned Elder Jiif, view humanity and animal life as destructive parasites that threaten the natural balance of the universe. Motivated by a radical, aggressive philosophy to purge all non-plant life, the Green Planet leaders scheme to launch a massive botanical
invasion of Earth. They attempt to manipulate Kibo, recognizing the young plant's latent, god-like potential to serve as the ultimate catalyst and weapon for their ecological crusade.Driven by fierce loyalty, Nobita refuses to let his friend be exploited as a tool for planetary destruction, sparking a high-stakes conflict. As tensions escalate, Kibo undergoes a profound internal crisis, torn between loyalty to his human creator and his natural instincts as a supreme plant entity. Dramatic battles ensue across surreal botanical landscapes as Doraemon deploys his secret gadgets to thwart the alien army. Ultimately, Nobita delivers a passionate, heartfelt plea emphasizing that coexistence, empathy, and mutual understanding are superior to forced eradication. Moved by this display of genuine love, Kibo harnesses his immense powers not for war, but to heal the rift between worlds. He willingly sacrifices his physical form to become the immortal Guardian Spirit of Earth's flora, ensuring lasting peace and securing a poignant, bittersweet farewell with a grieving yet profoundly grateful Nobita.