A and Un are twin artificial beings forged from battle components, originally designed as companions for Koto before being embraced as siblings. Their names originate from the Buddhist concept "A-un," representing the primal duality of creation and closure. A pulses with relentless energy, his exuberance a stark counterpoint to Un’s quiet, watchful composure—a yin-yang pair bound by purpose.

Serving as Koto’s familiars, they shift seamlessly between humanoid forms mirroring middle-schoolers and spectral, monstrous entities capable of flight and formidable strength. In their everyday guise, they don black blazers layered over crimson hoodies, paired with utilitarian black pants and shoes. Transformation heightens their contrast: A radiates fiery red hues, while Un embodies cooler blue tones, visually echoing their opposing temperaments.

Tasked with aiding Koto’s search for a mysterious black rabbit—a quest tied to her return home—they navigate the dreamlike distortions of Mirror Capital. Though their origins trace ambiguously to creations by Koto or the enigmatic Inari, their existence orbits Koto’s chaotic journey, emphasizing loyalty over personal history. Their bond with Koto threads themes of found family and synthetic purpose, their interactions weaving chaos and devotion into the narrative’s fabric without delving into individual backstories.