There have been many rumours over the last five years about the possibilities on a 3rd season. However there is not yet any concrete proof which indicates the continuation of the anime in any form.
- Season 2 (2010) followed Season 1 (2008) two years later. It's been five years since. This reduces the chance of a anime continuing.
- Season 2 departed greatly from the Manga series making it difficult to continue the original vision. Saving Chiho Hidaka and Uzume from Higa storyline is where this changes.
At least one anonymous person has posted that a 3rd season is coming and gave a hint as to when. The hint was simply in a jumble of numbers claiming that they didn't wish to lose their job over it and thus could only provide that much.
- Sometimes a Studio or Mangaka will choose to wait until a series is finished to allow a broader sense of the works to be translated to the anime medium.
The final date in the sequence of the numbers given is/was 4th November '15.
Regardless, chances of a 3rd Season are near non-existent.