Tales of Phantasia: Katararezaru Rekishi (テイルズ オブ ファンタジア 語られざる歴史 Teiruzu obu Fantajia Katararezaru Rekishi?, "Tales of Phantasia: The Untold History") is a side novel detailing the events that led to the fight between Dhaos the Demon King and four great heroes of the past, specifically AC 4207, in Tales of Phantasia. It was written by Ryuji Matsuri and illustrated by Shibusawa Kobo. The first edition was issued on May 25, 1999 by Dengeki Bunko.
Around a century prior to the present timeline events of Tales of Phantasia, a young woman, Winona Pickford, wanders in the forest near her home in search of a Unicorn, but instead becomes distracted by a golden light in the distance, leading her to an abandoned castle, where she is attacked by winged demons outside. This light radiates from Dhaos, who arrived on Aselia in a disillusioned state after being hurled through space from his home planet of Derris-Kharlan. Taking shelter within the castle, Winona is approached by Dhaos, at whom she aims her weapon, a crossbow, before he falls to the ground unconscious. She brings him to her home and nurses him back to health, which results in his recollection of the events prior to his decades of travel: that of his wife and followers dying for the sake of his mission. With this resolve, he concludes that he must obtain Aselia's Mana Seed at all costs. Upon discovering Aselia's World Tree Yggdrasill, he realizes that the use of magitechnology, a process that consumes mana at a faster rate than the magical tree can produce it, threatens his mission, the existence of magic, and the vitality of the planet itself.
- Dhaos (ダオス Daosu?) - The half-elven prince of a large and powerful country on a foreign planet, he ventures to Aselia for the sake of his home and those lost for this very cause. He soon befriends Winona but is later defeated by her and her companions regarding his intentions.
- Winona Pickford - A young human woman who performs in a circus troupe in the city of Midgards. She is pretty, cheerful, and apt in combat with a crossbow. She finds Dhaos in the woods near her home and nurses him back to health, but what soon blossoms into a friendship is later dissipated due to Dhaos's actions.
- Edward D. Morrison (エドワード・Ｄ・モリスン Edowaado D. Morisun?) - A half-elven researcher of magic who has known Winona for a few years. He assembles a team and accompanies her in storming Dhaos's Castle during his war with Midgards over their use of magitechnology.
- Alan Albane - A wandering swordsman recruited by Morrison to aid in the war effort against Dhaos, being one of the four members of the group that storms his castle and forces him to flee to another point in time.
- Carol Adenade - A cleric woman likewise recruited by Morrison for the sake of overcoming Dhaos, now deemed insane and who must be stopped.
- Reisen (ライゼン Raizen?) - A half-elven scientist who leads Midgard's military. Having clashed with Dhaos over his use of magitechnology in developing the powerful Mana Cannon, he uses this superweapon in his war against Dhaos, vastly overwhelming his demon army.