Auto-translated
She clearly bought the katana for her son. However, if we follow the logic of cooperation/working for the "Princess," her enthusiasm might have been driven by a desire to impress the higher-ups. But that's just speculation. We could take a risk and cautiously question her. We could take a big risk, sneak around, and look for clues. We could also have someone else stake out and follow the Mirai girl.
Added 14 minutes later
So, where do we start? With searching for the Mirai girl?