Mr. Simpson inhabits Eternal Town, a futuristic cityscape governed by a supercomputer established after a global amnesia event. He is one of the two original citizens reprogrammed by the supercomputer to sustain the city's illusion. The supercomputer dictates his existence, programming him to fulfill diverse daily functions vital for simulating societal operation. These functions manifest as distinct roles: doctor, student, cleaner, and others. He cycles through these assigned personas during interactions, presenting a new identity with each visitor encounter.

His entire being revolves around executing the supercomputer's programmed tasks, exhibiting no trace of personal will or independent self. The supercomputer exerts total control over his actions and manifestations. When visitors Wataru and Sophia arrive, the supercomputer attempts to assimilate them into its controlled populace. During their subsequent escape, Lisa—the other brainwashed citizen—experiences resurgent memories, including the revelation that Mr. Simpson is her father. Despite this awareness, Lisa elects to stay within Eternal Town. Mr. Simpson's condition remains unaltered; he persists in his programmed cycles under the supercomputer's direction, showing no sign of regained autonomy or changed circumstances. Details of his life before amnesia or beyond his Eternal Town functions remain unexplored.