Question: How did you do so that we cannot see/distinguish the lines and marks of the graphite of your pencil ? What kind of pencil do you use to draw the inner part of your drawing ? Do you have a special technique ? Did you blured it with special things ?
... I thought I have replied to your question... weird. Anyway, I usually use my Faber-Castell Contura 0.7 with a 2B graphite. Sometimes, for the skin and lighter hair, I use a silvery pencil and for the darkest shades I use a Koh-i-Noor Hardmuth 1500 7B. Sometimes I do blur them with a cotton, but for some, like my Akatsuki drawing, I prefer not to because it doesn't make the drawings that good.
I don't know if my advice would be good since I'm not professional and I've never taken any drawing lessons, so I don't know what other artists do. This is just my way of drawing. First of all, of course, I select the picture which I'll be drawing. Then I start doing the line art. When I'm drawing the line art I don't put pressure on the pencil so that the lines would be easy to erase in case I make a mistake. After I'm happy with the lines I darken them. The lines must be thin, so the graphite must be very sharp, I use a contura pencil. Then I make lines where the shadows are and after that I start shading it. I usually use my FaberCastell 0.7 contura pencil with 2B graphite for both lines and shadows. And don't forget to listen to some awesome music while drawing.