Dr. Easter operates as a freelance investigator and scientist under the Mardock Scramble 09 emergency ordinance, allowing experimental life-preserving technologies. He rescues Rune Balot from an attempted murder and saves her life using prohibited cybernetic augmentation to reconstruct her body. His central goal is building a legal case against her attacker, Shell Septinos, and he assigns Rune to gather evidence for this prosecution.

To aid Rune's rehabilitation and integration into the investigation, he provides her with Œufcoque Penteano, an artificial intelligence capable of shapeshifting, primarily appearing as a mouse. Œufcoque functions as both protective equipment and psychological support during Rune's adaptation. Dr. Easter's laboratory serves as the base for developing specialized case technologies, including Œufcoque's creation and deployment.

His involvement spans the legal pursuit of Shell Septinos, including strategic planning to infiltrate the BlueEgg Casino and retrieve critical evidence: a memory chip containing Shell's suppressed recollections. Failure to secure this evidence risks case dismissal and termination of all involved parties under Mardock Scramble regulations. Throughout this operation, Dr. Easter coordinates with Rune and Œufcoque while navigating threats from Shell's associates, such as the assassin Dimsdale Boiled.

Dr. Easter maintains professional detachment yet shows consistent investment in Rune's psychological recovery from trauma. His methodology merges forensic investigation with experimental cybernetics, prioritizing judicial accountability over personal vengeance. His technological and strategic resources prove pivotal during the casino mission and subsequent legal proceedings confronting Shell and the October Corporation.