Using the books "the wonderful wizard of oz," "the marvelous land of oz," "ozma of oz," and "the emerald city of oz" as sources, which were written by l. frank baum between 1900 and 1920, can you provide a summary of the main characters and their relationships?
Oz no Mahoutsukai is based on the first three and the sixth books in the Oz series by L. Frank Baum. Due to the latter two books not having been in public domain at the time, the series had to take large liberties with the plot.

