|Weapon: Seiryu spear|
|Blood Type: Unknown|
Puella Marionette (Foster Daughter)
Eos made her first and only appearance in Battle Arena Toshinden 4, as one of the unlockable sub-bosses.
The angel-like Eos is a biotechnologically-produced masterpiece of the Gerard Foundation. An incredibly powerful warrior, she can predict every move of her opponents, thus making her unmatched at fighting. However, her strange powers alarmed the members of the original Gerard Foundation, including the Shitennou (Chaos, Cupido, Gaia, Uranus) and even Master.
Eventually, Master and Uranus sealed off Eos' power to keep her from disrupting their own plans. Years later, however, she was found by Eiji Shinjo, who had become the new Master of the Gerard Foundation. Requesting that she release her powers to help him in his fight against an unknown evil, she managed to break Uranus' seal and pledged loyalty to Eiji as her new Master.
Eiji then gave her the Seiryu spear, Mondo's old weapon, which was one of the powerful Four Sacred Arms. As soon as she held the spear, it changed its shape into a beautiful jewelled rod. She then joined Eiji's team as one of the executives of the Foundation, planning to vanquish the approaching evil and return order and peace to the world.