Minori and The Mad Ventriloquist had a lot in common, although they didn't know it at first. Their childhood homes ended up being only a few blocks away from each other. Both were the oldest sibling, both had been homeless for a period of time. They knew what it was like to grow up one person in a huge city and have no one care. How they dealt with this was their only real difference, but that meant everything.
When they first met, Minori was wearing her police uniform. The Mad Ventriloquist thought that she was being very rude. Was she trying to start a fight? Did she just feel like she was better than us? Knowing what he does now, The Mad Ventriloquist realizes that wasn't quite it.
The Mad Ventriloquist didn't write the conversation down and he technically wasn't supposed to be listening so he doesn't really remember what was said. He remembers the murders though. They were nasty, brutal things. Organs ripped out, bodies hung from trees. Some people probably already know what he's talking about. We had been hit hard. Several members had died. The Mad Ventriloquist had lost a friend. Minori had lost a sister.
The police wouldn't let her investigate. Partially because she was a newer cop and partially because it was a personal matter. But Minori had to know, she had to find answers. So she went to the only other source of authority she knew.
And they assigned The Mad Ventriloquist to help her.