Disney and copyrights

[Stefan Persson]

Today I received the first Japanese W.I.T.C.H. compilation book, which 
is a Japanese version by the Japanese artist Haruko Iida that is based 
on the Italian original and produced for the Japanese publisher Kadokawa 
Shoten, for which Iida seems to be a regular artist.  What I noticed was 
the copyright statement:

© Haruko IIDA  2003  © Disney  Printed in Japan

How comes that this issue does not have the usual "© Disney and no one 
else" copyright statement?  If European and American artists can't claim 
any right to their own stories, how comes that this new (to Disney, that 
is) artist can claim rights for her stories?

Stefan