Kee, who has snapped megastars including Lady Gaga and Super Bowl sensation Beyonce, was arrested Monday on suspicion of obscenity after selling the books at his Tokyo gallery.
The 41-year-old photographer could be jailed for up to two years and/or fined up to 2.5 million yen ($27,000) if convicted.
Pornography is widely available and produced in Japan, but under domestic law genitals must be obscured, a process usually done through pixellation.
"I am stunned by the news of Leslie Kee's arrest," Yamamuro Kazz, a leading fashion journalist and magazine editor in Japan, wrote on his website.
He questioned police motivation for the arrest because Kee's works were available at a gallery event, a forum only open to people familiar with the artistic nature of it.
"The legal interpretation of whether genitals were exposed or not (and whether the work is obscene or not) is totally irrelevant to the intention of an artist," he said.
"Under their narrow interpretation, works by Terry Richardson and Robert Mapplethorpe are all considered obscene," he said, referring to prominent US photographers.
Popular model Ai Tominaga tweeted "I am shocked. I am shocked for Japan", and was joined by others online who expressed similar dismay. Twitter user @onda_natsue said the arrest showed how unsophisticated Japanese culture is.
In 2008, Japan's top court ruled that nude pictures by Mapplethorpe were not obscene, in a verdict hailed as a victory for artistic freedom in the country, ending a decade-long battle over the censorship laws.
The plaintiff, a Japanese publisher, filed the lawsuit after his copy of a Mapplethorpe book was seized in 1999 when he tried to bring it from the United States for personal use.