Katsumi Akagi

Ryos neighbor and classmate and is very kind and compassionate. She is also extremely strong willed and has no problems telling people when they are being idiots. Katsumi has been Ryos closest friend since early childhood and secretly loves him. Unknown to Katsumi herself she is also an Egrigori experiment with a vital part to play in Egrigoris master plan. Katsumi was in fact one of the original ARMScompatible embryos which is why she and Kei bear such a close resemblance to one another. However she was not given an ARMS implant for unknown reasons. After Ryos ARMS activates Katsumi is always beside Ryo trying to keep him calm and sane. Katsumi is taken prisoner by Egrigori in episode 11 but despite her long imprisonment she is always certain that Ryo will come for her. As of volume 18 she has seemingly been killed by the actions of Keith White and Ryo. White used Keith Greens time space jump to pull her into the path of one of Ryos attacks. Absorbed by Alice she is then seen alive and well when Black Alice is apparently defeated but she is the only one to see and offer a hand to her as she crumbles to death. This brief contact leads to the implant of an ARMS core inside Katsumis body: signs of its growing power are shown on many occasions in the form of grisly nightmares and increasingly unstable behaviour culminating in the massacre of a group of thugs. Katsumis ARMS are nicknamed Bandersnatch and can be viewed as the Jabberwocks nemesis. At full power she transforms into an exact copy of Jabberwock snowwhite in color and capable to generate ice as opposed to Ryos fire: its power is exceptional as opposed to the Jabberwocks ultimate ability of antimatter production and flame manipulation the Bandersnatch can freeze a townsized area to absolute zero and create whiteouts with a mere thought. Source Wikipedia