Dr. Magnus Brechtken, deputy director of the Institute of Contemporary History, told CNN the institute was "quite surprised" that public interest in the book was so strong in Germany.
The Munich based institute, which has previously published annotated editions of "Hitler's Speeches, Writings and Directives, 1923-1933," "Hitler's Second Book" and the diaries of ranking Nazis Joseph Goebbels and Alfred Rosenberg, said they initially planned to print 4,000 copies of the new edition.
Now, the book is in its 5th edition, with plans to publish a 6th slated for later this month.
Who is buying the book?
Feedback from the book's distributors suggests most people purchasing the new edition are academics or people with a keen interest in historical events.
"People who are reading history books in general, like a biography of Hitler or a book on the Third Reich, are interested in getting basic research information on a text which has not been available in a critical edition so far," Brechtken said.
He added that critics concerned that the new edition could incite negative outcomes from far right groups should not be worried.
The annotated edition counters Hitler's original text and is the antithesis of their ideology, he said.
"In my opinion, far right groups are mostly unhappy with the new edition," Brechtken said.
"We had no reaction from the far right because they don't like the book. For them, they want the text just as it was in the original -- they don't like that we have a critical edition, which is exactly why we have this edition."
"People who might want to read something from Hitler will never follow any of his thoughts when they are reading our book because Hitler is completely deconstructed in our edition," he said.
In a statement posted to the Central Council of Jews in Germany's website
prior to the reprint's release, council president Dr. Josef Schuster said, "The Central Council of Jews in Germany is convinced that Hitler's scorning propaganda 'Mein Kampf' must remain prohibited," but that the group would "not object to a critical edition, contrasting Hitler's racial theories with scientific findings, to be at the disposal of research and teaching."
How it was commissioned
At the end of World War II, the Allies transferred the book's copyright to the German state of Bavaria, with the condition that reprints would be banned.
When the book's copyright ran out on December 31, 2015, the Institute for Contemporary History decided to issue the annotated version to expose the "lies, half-truths and vicious tirades" of the Nazi regime, which ended in the deaths of millions of people during World War II
Brechtken says that in the 70 years that have passed since World War II, an annotated version detailing new research into the rise of national socialism adds an important academic framework in order to study the controversial text within a wider context.
The original version of "Mein Kampf," was around 600 pages long and featured a stylized picture of Hitler with the words "Mein Kampf" on a stylized red banner.
The institute's critical edition adds about 1,300 pages to the original text and drops the original artwork.
Republication of original still illegal
Hitler wrote "Mein Kampf", which means "My struggle" in German, in two volumes between 1924 and 1926.
He wrote the first volume -- largely autobiographical -- from a prison cell after the Nazi party was banned after a failed attempted coup in 1923.
The second volume, which details the Nazi's political ambitions, was written while on retreat.
More than 12 million copies of the Nazi leader's manifesto were originally published, but were burned after the war.
Several hundreds of thousands of "Mein Kampf" originals survived and can still be found in antique stores and historical bookshops, according to the institute.
Germany's justice system vows that any republication or distribution of the original without proper annotation remains illegal.