Ai Kitora/Plot

Background
When she was in B-Class, she rose through the ranks as a Gunner, but started using Scorpion because bullets were too Trion-consuming, especially with her low Trion. When she was still in high school, she became an A-Class member of Border. She was trained by Karasuma in the past, just like Osamu is now.

Introduction Arc
She first appears with Arashiyama, responding to an attack on the school.