Amazon Japan has recently updated their site and it reveals that Kamen Rider Amazons will be getting a second season! According to their site their site the second season is slated for Spring 2017. No other details are confirmed at this time so stay tuned for updates.
EDIT: The Hollywood Reporter has reported about the recent Amazon conference which lead to an agreement to add 12 different series to Amazon Prime Video worldwide. Some of those programs include Ultraman and Kamen Rider Amazons! Check out the link below for the full press conference coverage.