Twin Melodies (Part 1)
According to the book, during the time the Odi civilization was at the height of its prosperity, they ruled over a vast area in the north that was now part of the border between the Griffon Kingdom and the Gorgon Empire.
The borders were one of the most dangerous sectors, since even if the two countries were at peace from centuries, small and medium sized battles were a common occurrence.
Most of Lith's patients when he worked at the Academy were soldiers stationed in the north. After copying everything relevant to his research Kalla had to offer, she and Lith discussed for a while what was the best place to start his assignment.
"She's not a ring fairy, by the way." Since their last mind fusion Lith was aware that, by saving Protector, he had accidentally revealed Solus's existence to him. Kalla had witnessed both the conversation between the Ry and Solus back then and her protecting the unconscious Lith now.