Katsumi Akagi stands central to the conflict surrounding the Egrigori organization, defined by resilience and compassion. Genetically engineered through Egrigori’s experiments, she shares origins with ARMS-compatible embryos, lacking an implant herself but bearing a striking physical resemblance to Kei Kuruma that underscores their intertwined destinies. Her bond with childhood friend Ryo Takatsuki anchors the narrative, rooted in steadfast loyalty and quiet affection. When Ryo’s ARMS unit activates, she becomes his mental stabilizer against the Jabberwock’s corrosive influence—until Egrigori captures her, exploiting her significance to their schemes. Imprisonment tests her resolve, yet she clings to faith in Ryo’s rescue.

A pivotal intervention by Keith White warps spacetime to intercept Ryo’s strike, seemingly killing her. Contact with the disintegrating Black Alice, however, embeds an ARMS core within her, birthing Bandersnatch. This transformation fractures her psyche, triggering violent episodes and nightmares, including a lethal confrontation with attackers. As Bandersnatch, her cryokinetic powers counter the Jabberwock’s fury, evolving into a snow-white counterpart capable of summoning blizzards and absolute-zero cold—a stark contrast to Ryo’s flames.

Surviving Black Alice’s defeat, she marries Ryo, their child symbolizing Black Alice’s redemption and a cyclical close to Egrigori’s conflict. The epilogue frames her legacy as both a force behind Ryo’s evolution and a linchpin between ARMS’ past and its uncertain future.