Posca Pen is a well known artist's pen and without a try, I will not know how good it is.
Now I understand why so many artists choose and use this pen, because it is not only water based, the colours are very sharp and solid too.
I bought it from my last trip in Japan and cannot remember how much I bought it, but I am sure it is cheaper than on the net or from other country.
This is my little experimention to test the quality of the orange colour and I was amaze with its opacity. It can write at almost any kind of surface, but of course, not at all material. For example, in plastic as shown in the picture, the colour will come out easily if I scratch a bit with my nail.