Sonic Guardians-Vol 1

There are many worlds & dimensions in our universe & there are people who can travel wherever they please. Sonic & his friends meet a group of strange girls from a different dimension who seem to know them. But how would they know each other if they've never met? Sonic & a few others have been getting strange visions & dreams that seem to be important & they have all been occurring after the group of girls arrived. What does all of this mean? Is Mobius in danger or is all this just coincidence?