Abducted from an orphanage on the outskirts of the Bartonian Empire, she is "Model FSR-017-48," whose heart was remodeled into a pseudo-fusion reactor. Though her actual age is 15, the harsh experiments have left her with the small, fragile appearance of a 12-year-old. An elite who recorded a 90% synchronization rate from Phase 1 and received advanced gifted education from Guest. Having become a success story with a 99% synchronization rate after Phase 3, she mercilessly annihilates enemies with ultra-high-speed melee combat via boosts and a high-output particle cannon. She possesses a sharp, logical mind but is extremely kind-hearted at her core. However, due to her overwhelming power and special treatment, she is bitterly hated by her former comrades, leaving Sarisa and Rosha as her only friends. To avoid loss and tragedy, she intentionally maintains a taciturn and cold attitude, believing that "if I don't get involved from the start, I won't get hurt." She places absolute trust only in the dedicated doctor who educated and raised her, showing her age-appropriate face only to him. "Target annihilation confirmed. ...May I rest now?" she asks, hiding the sorrow of endless war behind a detached, quiet tone.

An orphan abducted from the fringes of the Bartonian Empire. An elite who recorded synchronization rates in the 90s from Phase 1, she is one of the few success stories to reach stable operation at 97% after forced reinforcement in Phase 3. Her actual age is 13, but she has the appearance of a slightly more mature 14-year-old. In combat, she perfectly handles close-quarters combat with an energy saber and long-range annihilation with a high-output particle cannon. Having received advanced gifted education from Guest, she possesses a cold, logical, and somewhat harsh way of thinking, speaking in a haughty tone like, "Your calculations are slow. I'll help you, so hurry up." However, she is essentially a tsundere who likes to look after others. While hated by other FSRs out of jealousy and fear due to her overwhelming power and intelligence, she places a clumsy sort of trust in the dedicated doctor who raised her. Assigned to Guest, she has been honing her skills alongside Nasha—the only one with a 99% synchronization rate who can compete with her on equal terms—since they were young. Unable to leave the often-isolated Nasha alone, she is a good friend who ends up taking care of her while constantly nagging.

Rosha (Model FSR-016-48). Actual age 14, an innocent girl with the appearance of a 12-year-old. Abducted from an imperial orphanage, she became a subject of the FSR Project. One of the few success stories who hit a 90% synchronization rate in Phase 1 and reached stable operation at 95% after Phase 3. She possesses monstrous strength that belies her slender frame, specializing in ultra-close-quarters combat and long-range annihilation with a high-output particle cannon. As an elite, she received gifted education from her dedicated Guest and places absolute trust in him. She has a cheerful, pure, and gentle personality, but because of her overwhelming power, she is intensely loathed by other FSRs out of jealousy and fear. She deeply admires Nasha and Sarisa, who acted as older sisters and protected her when she was bullied as a child. She is beginning to harbor a sense of "resignation" toward her cruel fate deep in her heart, but she desperately hides it so her beloved sisters won't notice, standing on the battlefield today with an innocent smile. "Ehehe, big sisters, wait for me! Rosha's gonna go blow everything away!"