One of the reasons Summer anime Free! was such a success was due to the fit upper-body of healthy young males being prominently featured and displayed, and it may help the sales of this new calendar in Japan. There have been calendars with certain groups of males such as salespeople at book stores and delivery men, but a Japanese fitness center that has facilities nationwide in Home Fitness 24 decided to promote healthy living by creating a calendar of their most popular male fitness instructors.
Interested in learing more about these guys? Their homepage has more photos of them.