The 200 stone is used to remove material, redo the line of the knife, reestablish the angle of the edge, in short, all the important basic work of sharpening.
 
Arato-kun is very abrasive and allows quick repairs.  This is the coarse grain stone that I use by default, that is to say for almost all knives. The abrasion is clear and progressive. 
Its pink color comes from its abrasive material, pink alumina (aluminum oxide), which is very resistant over time. 
I highly recommend this large size (because it also exists in small) which brings real comfort i