When Legion, the mentally unbalanced mutant son of Professor Charles Xavier and Gabrielle Haller, travelled back in time in an attempt to kill Magneto, he accidentally killed Xavier instead, creating a splinter universe known as the Age of Apocalypse. In that reality, mutants became the dominant species of the planet. Apocalypse rose to power enslaved humanity.

In this reality, Weapon X (Logan) and Mariko Yoshida had a romance before the ascension of Apocalypse. This romance produced a daughter, whom Mariko named Kirika. Weapon X was unaware of this birth, and following the destruction of Japan joined the X-Men while Mariko joined the Human High Council. Kirika became the property of the evil geneticist Sinister, although the circumstances behind her captivity are presently unrevealed^[1].

Following the fall of Apocalypse, Kirika was found in one of Sinister's old labs in a container marked "X-23" by Magneto and the X-Men. Kirika surprised them when she exhibited the ability to extract three bone claws from each hand, making the X-Men realize that she was related to their former comrade. Kirika was invited to join the X-Men, who were now government sanctioned bounty hunters trying to capture all the mutants that aided Apocalypse during his reign. Kirika was trained by Magneto himself, who bonded her skeleton and claws with Adamantium^[2]. Magneto sent Kirika out to find Weapon X in Canada and convince him to return to the X-Men^[3]. After explaining to him what she knew of her origins and helping Weapon X take down Northstar and Aurora, former minions of Apocalypse, she convinced him to return to America with her^[2].

Back in America, Kirika broke up a fight between Weapon X and her uncle the Silver Samurai before the team was called to Washington D.C. to battle Amazon, Cannonball and Icarus^[4]. This proved to be part of a plot to allow their sister Paige to get revenge against the X-Men for leaving her to die during a mission. A battle erupted and all the Guthrie's were slain. Kirika mortally wounded Paige, Paige revealed to the X-Men that Magneto was secretly preventing Sinister's capture^[5].

Kirika listened as Magneto explained that he was blackmailed by Sinister to keep the secret that Jean Grey was responsible for saving the world from nuclear holocaust during Apocalypse's downfall. Kirika joined the X-Men in tracking Sinister to Liberty Island where she clashed with members of his Sinister Six^[6]. In the final battle, Sinister was defeated and Kirika aided Weapon X in slaying him by impaling him with their claws. In the aftermath, Kirika had Psylocke use her powers to unlock her memories and learn the truth of her origins. Knowing that she is the biological child of Logan and Mariko, Kirika accompanied the Silver Samurai, Sunfire and Psylocke back to Japan so that she could be reunited with her mother^[1].