Mirage's fourth volume of the Teenage Mutant Ninja Turtles series.
Issue #31 was completed before sale of the Teenage Mutant Ninja Turtles to Viacom. Peter Laird, who had placed the comic on hiatus due to his involvement in the 2007 TMNT movie, decided to post it on his blog for fans to see the issue.
See TMNT: Teenage Mutant Ninja Turtles (Peter Laird) #31 (October 17, 2010) [on Peter Laird's online blog only, http://peterlairdstmntblog.blogspot.com/2010/10/tmnt-volume-4-31.html
, retrieved 18 April 2011]
Eventually, issue 31 and an issue number 32 were released, 32 before 31. Issue number 32 was released on May 2014 and 31 on April 2015.