I can make jun come to the cafee too.

And I would wonder who going to be a friend for jun, preferable someone who makes him blush/explode occasional often //avoids bullets

For plot ideas I will trow a idea here

A old NPC woman faints in the mids of cafe everyone comes and help her finding she is bleeding, or hurt otherwise.
She recovers quite fast and in thanks she insist on everyone to come with her. Calling them by name. Which would maybe confuse the ones who didnt gave her their name. But they go.

This lady then takes them down a street, and things gets triply. They dont know where they are but they know the city as their pockets. She leads them to a small shop and says them to take what ever they want. 

we could either go slowly or fast from this point. Slowly is for them look at the many weapons, and stare at the lady like '' you crazy gifting us weapons'' 
While the lady say they a rare artistic pieces, that sell for a lot. 
They got the things and go. Or at least try.

The fast way is for the show to get attacked they grab the first weapon in hands to not die. The NPC urging them to pick something. While the NPC holding the ground fighting first.

I personally like when the situation abort ends. They blink and they are in the cafe no one saw the old lady NPC. No time passed.
Or they blink and found them self 12h later in bed. Tomorrow they just cannot help themself and go to the cafe.

A another idea I can offer is following.

A ridiculously rich man enters the cafe and our characters are the only ones there he congratulates us announcing he is inviting us to a lunch party. He gives us cards that had the pictures of out weapons and a hint of what our magic is.

He leaves then. We part and again fast and slow way.

Fast get atacked when we are alone, or in group of at most 2.
Slow nothing happens and we actually go to the place we are invited, but its a run down place. We explore and got attacked. 

Hope this gives you guys some inspiration