Kal Duran was born Altrui`se`Kal`duran Ayersoth`e. He was born in 6 B.C; in the Kingdom of Corinthia. He was born into Nobility and became a Corinthian Knight. He survived the sinking of Corinthia at the hands of his cousin; Gabriel Argadon. Now as a Guardian Apprentice, who seeks to become a stronger Guardian than Gabriel; has been sent to Tokyo University to finish his education before his training can continue. By day he's a University Student; by night he is the vigilante Night Walker. While continuing his education, he has been given a number of missions by Gabriel Argadon, one of which is to guard the Oracle of Destiny.
Throughout his adventures, Kal battled against Fallen Angels, Unknown II’s, Shadow Wraith II’s and even Demigod’s in the defense of the Oracle of Destiny. During his second semester at Tokyo University, Kal’s Guardian missions intensified. Kal traveled to the World of Anearoth in order to protect Selef Baradash until Selef made up his mind. Then, a few days later; Kal’s Dual Soul awoke due to Chaos. Kal fought against his other self; his complete opposite and eventually defeated him.
Enraged at the loss of a potential new minion and seeing an opportunity to capture the Oracle of Destiny while Kal was waylaid, Chaos sent Selef Baradash to kill Kal while he took the opportunity to capture the Oracle of Destiny. Kal defeated Selef; banishing him to The Void. Kal then went after Chaos and the Oracle of Destiny was saved by Gabriel Argadon and whisked away to the World of Kalan. Chaos retreated and Kal was given another mission that was related to Chaos and his manipulations. Kal traveled to Aldea during the Reunification Wars and fought against Princess Sakura and awakened her Aldean-side; which was dormant thanks to the emerged Shi’ado-side.
Kal used his wits and convinced Princess Sakura to fight on the side of the Aldeans. Prior to his mission to Aldea, Kal was given a mission to protect Princess Sakura while she traveled to the underwater Kingdom of Corinthia in order to have her Shi’ado-side sealed. During that mission, Kal encountered Demon Eater; who had come to Corinthia in order to kill Princess Sakura and thus kill Lord Vahloren. Kal defeated Demon Eater and saved Princess Sakura’s life. After Kal’s return to Corinthia from Aldea, Kal found out that he had a long lost Sister; an illegitimate child from his Father’s affair with an Aldean woman.
Kal found out that his long lost Sister was stuck in a Dreamscape, and that Selef Baradash was also in that Dreamscape and trying to escape back into the Multiverse after escaping his imprisonment in The Void. Kal traveled to his younger Sister’s Dreamscape, fought against Selef Baradash and rescued her from her delusional dream and her enchanted slumber. Kal was then given an assignment to raise his younger Sister.
A few weeks after rescuing his Sister, Kal went to an Obon Festival with her and Watanabe Saki. Then, Demigod and Lord of Darkness; Odin, appears and confronts Kal for the whereabouts of the Oracle of Destiny. Kal fights against Odin and gets defeated. Kal’s Spirit Sword awakens and whisks him away to another Dimension. Kal is trained by his Spirit Sword on how to use it and after 1,000 years, is sent back to his Universe; a few minutes after his defeat by the hands of Odin.
Kal confronted Odin once again and severely injures him. Odin retreats. Kal, with the help of Wataru Watanake; goes after him and travels to the World of Purim. On Purim, Kal meets Hasegawa Kaito and joins The Legion to confront Odin and his evil company; which controls the Kingdom of Westphalia. Kal, Kaito and Wataru confront Odin’s pseudo-Nephilium. Shadow Wraith appear and Kal leaves the Physical Realm in order to battle them.
Odin is subsequently defeated by the Maken; but not before he sends Lucifer the location of the Oracle of Destiny. Kal and Wataru leave the World of Purim and travel to the World of Kalan to thwart the destined invasion of that world by Lucifer’s Dark Army, the Vellion Alliance and the Maken.
Once Kal arrived on Kalan, he met Kyoshiro Valco; whom he hadn't seen since the early days of his training. Kal encountered Kaito, who had become a Ancient Guardian. Kal teamed up with Galactic Guardian Alika Thalmus to battle the ground forces of the Dark Army and The Maken while Kaito battled the Vellion Alliance forces in space. Kal fought against his other Soul; Eric Ryusei, who had become Nightmare 05 "Avenger" of The Maken. Kal banished Eric to The Void after Eric killed Alika. Kal also fought against Shino Kenzu of The Dark Army and Eris and Karite of The Maken. Eris was taken out of the battle early and then Kal and Karite went at each other. Karite retreated with The Maken after Gabriel Argadon showed up and defended his apprentice from Karite's unholy assualt.
Kal met with Kaede Sanada and her handmaiden and the group returned to the Eiradeyn Universe after the War of Kalan was over. Once back on Earth, Kal returned back to his studies and took command of Civil Defense Division Zero: The Civil Defenders.
Kal Duran then fought in "The Year's War" against Dark Lord Kahrite; Nightmare 00 of "The Maken" and his forces. In the final battle against Kahrite, Kal destroyed the Orb of Anubis; returning the original Multiverse to it's original form.
Returning home to his home Universe, Kal sacrificed himself; saving Gabriel Argadon's life and rescuing Kaede Sanada from Demon Eater. Having his physical death, Kal ascended and became the Ancient Guardian of "Truth and Knowledge".
Kal made his first appearance in Aldean Chronicles. He later appeared in Guardian Apprentice as the protagonist and has cameo appearances in Far Star Chronicles.