I have Corsa B Coilovers in mine. You need to file/ream/drill the holes on the bottoms of the front legs out from M10 (Corsa) to M12 (K11), not difficult but a bit time consuming with a file!
Same with the rear lower mounting holes; they need to be drilled to go onto the M12 stud on the micra.
The corsa front legs are short as ****...I had to make up two 12mm spacers and put them between the top of the strut and the bottom of the turret so the shell of the car is sitting on the spacers, which then sit on the top of the suspension unit. Not sure what other people do but I had to open up the black mounting plate thing with the rubber bush in it and take the K11 strut out and put the corsa one in. If you open the bonnet and look into the top of each strut you'll see a big nut at the top buried in a rubber bushing; that bit.
The rear corsa B Springs are a beehive shape, but the K11 ones are cylindrical. I have the corsa springs put in my retainers but they foul the body of the car when they're compressed beyond a certain point and make a pretty horrible sound so I'm considering just going back to the standard micra rear springs and cutting them down, which I believe is what most do. There's a sticky on here somewhere that's the go-to!