The wraparound jacket of Prison School‘s 19th manga volume has announced an OVA of the series. It will come bundled with the 20th manga volume on March 4th, 2016.
source: myanimelist
While it’s true that getting an OVA isn’t always a measure of success (Isuca and Triage X were both flops and both got post-series OVA), I can’t help but feel that this announcement is an indicator that a second season of Prison School might be coming in the next year.
It should be interesting to see what the OVA will cover, since the first season hit a natural stopping point and the manga is fairly straight forward without much in the way of spinoffs or backstory. Maybe it will just be anime original and focus on fanservice? Or maybe it will serve as a teaser for another season? Either way, it should be fun to see what JC Staff has planned here.