Guess you can be quite safe on the base. The base is actually just a layer of paint on the wall, to even out the different colors you have on your existing walls (eg. cement, previous color, dirt). After the base color, they will paint with what you have selected using Nippon.
What we saw is that they usually paint about 3 layers altogether (base, first layer of paint and then second layer or paint) eventually, your color will turn out just fine. Even after that, due to moving of furnitures or other works that resulted in scratches, they will come and repaint again.