Board Thread:Questions and Answers/@comment-26546086-20170124171520/@comment-25942629-20170211234034

Both the Nagoya episodes and the first twelve are considered to be season one in English. Season 1 part 2 was released back in September.

http://seraphoftheend.deviantart.com/journal/Season-1-Part-2-Collectors-Blu-Ray-DVD-Released-636943565