KK Slider, the guitar-loving dog, can come visit your island and play a concert for the residents of Animal Crossing: New Horizons. There are, however, a few steps you will need to take to get there.
After upgrading Resident Services from a tent to a proper building, go talk to Tom Nook. He will say he has something he wants your help with. Sit down and ask what it is, and he'll tell you he wants KK Slider to come.
For the concert to happen, you'll need an audience, so you'll need to get more visitors to get to your island. You'll need to place a campsite somewhere and Tom Nook will give you what you need to set it up.
After setting up the island for visitors, you will also need to work to get more residents. Tom Nook really wants a big audience for this show he has planned.
The third piece of the puzzle is to make your island beautiful. Make sure there are plenty of flowers, furniture, fences, and other things for your residents. Pull weeds and put away any trees that get in the way. Talk to Isabelle whenever you need help figuring out what to do next.
After that, it's a waiting game. Keep working on your island and wait for the big KK Slider to decide it's a good place to visit. He will contact Tom Nook when the time is right. Once he arrives the first time, he will fall in love with the island and go every Saturday to put on a show.
