I just baught an artbook containing the pictures 
of all the gengas Yuki Nobuteru has drawn for X. 
I found the genga corresponding to my Kamui A1 
key cel (link above, it's in my gallery if you 
want to see it). It means that this cel was made 
from a genga Yuki Nobuteru made himself. But does 
it mean that he made the douga and/or the cel ? 
There's also this katakana writing on the douga 
that seems to be "yu-ki" - What else could it 
be ? - Is he used to writing his name on the 
dougas he draws ? What do you think about that ??