This paper examines the human-nonhuman assemblage visualized by Wes Anderson in Isle of Dogs from the perspective of New Materialism. Anderson makes nonhuman animals and objects, which have been disparaged as helpless and passive, speak and become visible, revealing their vitality, power, and agency. In particular, the dogs, various trash, and humans that appear in the film form an assemblage, exerting political power to overthrow anti-ecological and fascistic political forces and create a more democratic and ecological community. Trash Island, imagined in the film, symbolizes an uninhabitable Earth ruined by the pandemic and climate crisis of the Anthropocene. Set in the ruins of the Anthropocene, the story of Atari and the stray dog Chief condenses the drama of co-evolution between dogs and humans. The relationship between Chief and Atari, which had been hostile to each other, begins amid Chief’s sympathy and reluctant response to Atari, and Atari’s constant attempts to establish a relationship, prepared to fail. Afterwards, through a kind of obedience training to tame each other such as fetching, bathing, and eating snacks, Atari and Chief co-constitute each other as capable partners. This can be called ‘becoming-with,’ a guide to survival on Earth in the Anthropocene. On Trash Island, various kinds of trash are neatly sorted by type and color and piled up like a mountain. These trash brilliantly reveal their unique materiality, vitality, power, and identity. Trash objects, which were considered dirty and worthless, are revealed as vivid things that cannot be reduced to existing contexts and signs. This movie is about anti-ecological life vs. ecological life, the confrontation and conflict between two forms of life. Dogs facing euthanasia and the humans who save them and try to live with them can be said to be an ecological class that seeks habitable land against Kobayashi, an anti-ecological class.