Manga Tools for each steps -Water Color-

Pencil drawing
Pencil

Inking
Line art pen (water proof) / manga pen with waterproof ink
Paper (for watercolor and smooth surface one if you ink it with Manga pen)

Trace the pencil line use a light box ...

 

..or draw with a pale pencil in very light touch then ink it.

*Don't use an eraser on the paper, it harms the surface!

Lightbox (You can use a glass table instead)


Painting 
Watercolor ink (Transparent one, not acrylics, Gouache.)

Water brush-pen(Video) or Saishiki Hude彩色筆 (Japanese art brush)

White ink. Waterproof, Brush for white ink. 

Fixative. It's keep the white ink steady. (I don't use it)