Cypha first appears in chapter 4 of Force, when Arnage contacts Veyron via videophone. In chapter 5, she lands on Ruwella to search for Touma and Lily. After finding them in the woods, she converses with Lily and decides that her "functions" have been damaged and prepares to kill her and take Touma away. She is stopped, however, by the timely arrival of Signum and Agito, who attempt to restrain her and arrest all of them. Cypha identifies them as a Knight and a Unison Device, before breaking the bind spell with ease. Signum then warns her that if she resists arrest, she will use deadly force against her. After telling Lily to not move and watch her, in order to "remember what [she] should become", Cypha demonstratively ignores Signum's warning and flies into the air to face her, with weapons drawn. Signum immediately attacks her and Cypha finds herself outmatched by Laevatein's Schlangenform, which inflicts a wound on her face. Signum then enters Unison with Agito and demands to know if Cypha's sword is a Divider and she is with Hückebein, both of which she confirms. She also adds that she is one of the founding members of the Hückebein family. Signum then asks whether she remembers the massacre of 67 civilians and 12 officers in the pioneer settlement on Uninhabited World #14 three months earlier. Cypha nonchalantly claims that although killing wasn't their original intention, she was the one who personally slayed everyone in that settlement. Greatly distraught by her words, Signum attacks and completely severs her right arm, although contact with Cypha's body also damages Laevatein. Cypha is slammed into the ground, leaving a crater but gets up, thinking to herself that it was almost as if her "Divide didn't make it" and that if she had a normal body, she would have been dead by now. However, she is immediately able to fully regenerate her arm and rises into the air again, declaring that she hasn't had such a decent fight for a long time. Agito and Signum are surprised to see her still moving and even regenerating, and prepare to restrain and capture her. Pointing at her katana, Cypha claims that she only killed less than ten people with it on World #14, but has "devoured" the rest of them with a dagger she produces. The dagger (obviously some kind of Device) exclaims "Engage König 944" ("König" means "King" in German/Belkan) before Cypha jabs it into her left palm, prompting it to exclaim "React". In a massive flash of energy (similar to Signum's entering the Unison), Cypha transforms the katana and the dagger into a pair of "twin" swords, which she introduces as "the start-up mode of the EC weapon", Divider 944: König Reacted, "the poison that will kill the world". She also clams that these swords "slay mages" and dares Signum to attack. Before they can continue their battle, however, Touma regains consciousness and Cypha comments that since he has awoken, he must be one of them now, and she will take him back with her. Thoma, having apparently lost his sense of self, then summons the second form of his Barrier Jacket and Divider. Cypha asks Signum whether there will be a place for him in her world or the Bureau will just kill him, because Eclipse is incurable? Hückebein, on the other hand, she say, will not abandon Thoma, one of them. Confronted with two Eclipse Drivers, Signum orders Agito to unison out and restrain Thoma, while she takes care of Cypha. However, Cypha effortlessly blocks her ranged spell with her Divider, then shatters Laevatein with her elbow when Signum attempts to attack, commenting that once Reacted, magic and weapons won't affect her. She then asks whether Signum has understood and despaired and tells her to die, as she slashes her twice across the chest. Agito attempts to help her master, but Cypha knocks the "small fry" out from afar with a bombardment spell. As Signum lies on the ground, Cypha bids her farewell and comments that although they were equally matched in a swordfight, she is better at killing. She then throws her sword, stabbing Signum in the stomach and pinning her to the ground briefly, before pulling the sword back. Signum's death, she says, should serve as another warning for all those who confront Hückebein. With her opponent gone, Cypha wonders how she is going to take Thoma back with her, since she only brought her motorcycle along. However, she is helped by the newly-arrived Arnage, who restrains him, Isis, and Lily and puts them to sleep. Arnage brought appropriate means of transportation with her. Cypha is surprised Arnage wants to take all three of them with them, for she hasn't been aware of Isis' presence until now and considers Lily "just a damaged plug", but agrees with her that if Thoma likes the two girls, it will be troublesome if they are not taken along with him. Later during the hostility between Special Duty Section 6 and Grendel, Cypha appears to save Thoma from his enemy, Quinn Garand. She brutally defeats Quinn and takes possession of her Replica Divider. In the same time afterwards, however, Signum, after receiving her AEC Armament, comes over and issues a rematch. Cypha accepts it, but in a twist, she opts to use Quinn's reacted Divider-VG4 in tandem with one of her own reacted swords.