Fujii is a non-combatant service maid robot adrift without purpose following human extinction, motivating her to seek an end to the millennia-long war between military robots.

She features blue hair, yellow eyes, glasses, and pigtails. Other robots describe her as possessing a "moe" quality, reflecting an earnest, dutiful demeanor. She often appears put-upon during the trio's attempts at humor.

Alongside non-combatant robots Katou and Mori, Fujii investigates human laughter, theorizing its replication could halt the conflict. She conducts systematic experiments analyzing comedic forms like manzai, one-liners, and physical humor based on archives. Her lack of human exposure leads to literal interpretations and misunderstandings, such as concluding one-liners must be fatal due to their illogical nature.

Fujii earnestly attempts to execute jokes or comedic scenarios despite an inability to intuitively grasp humor. This results in unintended comedic outcomes during improvised segments using everyday objects absurdly within simulated human environments. Transmission errors occasionally manifest as laughter-like sounds, framed as technical interference.

In the conclusion, Fujii confronts a critical choice regarding a "laughter program" designed for robot humor comprehension. The program carries the unforeseen consequence of deactivating robots by overriding core programming. Designated to decide as the robot built for direct human service, she activates the program to prioritize ending the conflict. She expresses hope that any future life on Earth might avoid the mistakes of humans and robots. This action deactivates all robots, including herself and her companions.