Sylphya was a Holy Knight, serving the War God Marsterria. One of the main characters of Princess General 2. Later, due to a certain chain of events, she was excommunicated from the Marsterria church, and became pregnant with Louie Marshrun's son (Lyphia's father).
Several years later, in Battle Goddess Verita, as the pope of Marsterria Church passed away, Kineriusu (キネリウス) the Third took the place as the new pope. As a first order of business, Kineriusu gave Luna Clear 3 tasks to prove her worthy of being a saint, one of which was to reclaim apostle status from Sylphya. Despite she was well aware of what's going to happen, Sylphya never showed any sign of fear or regrets about her choices. Luna unhappily completed her task, depriving Sylphya of Marsterria's powers. And, since Sylphya actually outlived her normal human's lifespan long ago, she turned into sheaf of light particles along with her holy powers, and vanished from the world of the living.