The Master of Synapse rules the floating realm above Earth, commanding the artificial Angeloids designed for combat, surveillance, and other purposes. His primary objective is reclaiming the escaped Angeloids, Ikaros and Nymph, and eliminating Tomoki Sakurai, viewing humans as insignificant and unworthy of Angeloid technology.

His history reveals centuries of intervention on Earth. He deployed Ikaros in Uranus Queen mode to destroy the Tower of Babel, perceiving human ambition as a threat. He later orchestrated the replacement of the deceased Sohara Mitsuki with a clone to ensure Tomoki retained memories of his childhood friend, manipulating human lives for Synapse's undisclosed objectives.

He dispatches multiple Angeloids to Earth. After the Harpies fail, he sends the close-combat specialist Astraea to recover Ikaros and Nymph and kill Tomoki. When Astraea rebels, severing her neural chain after refusing to kill Nymph, the Master escalates by deploying Chaos, a second-generation Angeloid designed for superior adaptability and combat.

His relationship with the Angeloids is authoritarian and exploitative. He imposes absolute obedience through neural chains, punishing defiance with severe reprogramming or death. This is evident when he orders Chaos to eliminate the rebellious Astraea and later abandons Chaos after she sustains damage, viewing Angeloids as disposable tools.

His downfall occurs during the final conflict. Underestimating Tomoki, who infiltrates Synapse, the Master has his core destroyed using Ikaros' power. Defeated and weakened, he is imprisoned within Synapse by Ikaros, Nymph, and Astraea. They establish a new order with Angeloid self-governance, ending his tyranny. His imprisonment signifies the rejection of his ideology and the emergence of Angeloid autonomy.