Teo, a fox-like being inhabiting Oblivion Island—a realm where forgotten human-world objects reside—collects discarded items out of necessity, as his species cannot craft their own. His society relies on stamp cards as currency, shaping his transactional worldview. When he steals Haruka’s key, he bargains to help her retrieve her lost mirror in exchange for her keychain, prioritizing pragmatic exchanges over altruism.

Driven by the ambition to build a functional airplane, Teo seeks both innovation and escape from his constrained existence. This goal culminates in the film’s climax, where his makeshift plane proves instrumental in rescuing Haruka and thwarting the antagonist. Though initially aloof and self-serving, his loyalty emerges when guilt consumes him after betraying Haruka under pressure from the Baron, who bribes him with stamp cards to seize the mirror.

His evolution from self-preservation to heroism unfolds as he redistributes his stamp cards to rally the island’s inhabitants, uniting them to construct the aircraft. Teo’s emotional vulnerability surfaces when Haruka is captured, his distress escalating to visible tears. During the final confrontation, he puts himself in danger to save her, underscoring newfound courage and accountability.

Interactions with allies like Cotton, a plush toy evoking themes of neglect, and adversaries like the manipulative Baron reveal facets of his personality: torn between ambition and ethics, haunted by memory’s fragility. In the resolution, Teo orchestrates Haruka’s return to the human world, symbolizing his growth beyond transactional bonds and acceptance of impermanent connections.