I got to give you people credit.

[Ironos]

This is the description IN GAME.:

If you mouseover the actual buff of Suiton, given by using the Suiton Ninjutsu, it says something along the lines of your body being veiled in light bending water, enabling actions that normally require the Hidden status.

I do agree that it should state that on the tooltip of Suiton itself, but it is there, just out of the way placement.