Luna was observing Akiro since they had caught the thief. He was hell-bent on intimidating the man who sinned as it involved dark magic. She was the one who was connected to an Unknown Goddess yet the other was more hostile than her.
'My purpose at first is about the sabotage they had done on our group but I didn't expect it to be deeper than that,' she thought. There were more things she did not know about Magic Academy despite reading so much. Since it was about dark magic and the devils who were the source of it, there was one thing she could only do.
It was to continue learning about the Unknown Goddess' set of spells. Even though the spell book about those set of spells did not explicitly tell who the Goddess and what her purpose was, the magic spells it offered shared a common purpose. They were ruthless among the evil especially those with dark magic.