Aiko contemplated in Foss’s words. Aiko’s mind was currently filled with regret and guilt which became a bud of doubt in Hajime as the hatred swirled around. Hajime was certainly Aiko’s important student, but Shimizu who was also a similarly an important student to her was murdered. The moment she understood he was an existence who, according to situation, would deprive the other students of their lives. She recognized Hajime as a threat who would deprive her of her important people. Even so, Hajime was also her student, she couldn’t simply cast him away. It was the same reason why she couldn’t just abandon Shimizu, who tried to commit mass murder. That’s why she was confused since because didn’t know what to do. Though Aiko herself thought she had a difficult personality, she couldn’t help it. Hatayama Aiko was a ‘teacher,’ after all.