On all of the drawings I've ever seen of his, he
usually signs his name as "Nob" (in roman letters)
sometimes surrounded by a box.

I don't expect he did the douga, and the cel would
just be a copy of that painted by a cel painter. 
(I can't really see an animation director or
character designer painting cels for a
production).

-- 
Matt Martin
http://nekomusume.net