I need help identificating a gag manga that was serialized around 2003~2004
Fat chance it's Kungfu Komang.






  A boy named Komang learns kung fu and meet many friends along the way.


From the images above, you can spot:


an old man with a really long bold head [you mean bald maybe?]
a ninja [dude with google above his head]
a magician thief (Cased Close, Phantom Kid) [dude with hat and tie in his neck]
a fighter [I think the one you meant by this is Komang, dude in orange suit]  


Soooo long since I read it, the only thing I remember is that it's pure comedy, the old man was some kind of a master/teacher (for martial arts?), they all live together, and ruckus happened between them in every story.