Sophitia maintains a helpful, motherly facade as Granseed Academy's librarian, concealing her true role as leader of Physis—a cult dedicated to spreading destruction and reviving the evil goddess Nestra. She covertly manipulates academy events and individuals toward the cult's goals. Her background connects to the creation of Nemo, a homunculus designed as the "Son of Destruction" under Amis Germain. She orchestrates Nemo’s escape and his assumption of a human boy’s identity and memories. Later, she exploits Gareth’s trauma over his clan’s destruction by Physis, feeding him false intelligence about Nemo’s origins and a threat in Granseed’s old library. When sealed dark power threatens global disaster, she corrupts Gareth by augmenting his abilities to kill Nemo, weaponizing his rage and guilt.

As the true antagonist, Sophitia masterminds Physis’s resurgence and the spread of destruction, aiming to unleash the academy’s sealed dark power. During the final conflict, she undergoes a grotesque metamorphosis into a monstrous "Pregnant Pus Titan," embodying the corruptive force she serves and culminating her efforts to channel annihilation. Her manipulations include attempting to eliminate Gareth after his usefulness ends, though he survives via his darkness powers. In the climax, she battles Nemo and Faria. Nemo embraces his true form and the legacies of Jenius and the original Nemo, combining their residual power to recreate the Book of Time. This act traps Sophitia and the dark forces within the book, permanently sealing her threat at the cost of extinguishing Jenius’s soul and Nemo’s powers.