The 50th issue of Shueisha's Weekly Shounen Jump
will announce that Gintama
will include an OVA bundled with volume 58, to be released April 3, 2015. The issue with the announcement is coming out on Monday. The tagline for the bundled anime reads, "It's time for all the Yorozuya members ...to wake up just one more time."
Source: Scan via ANN
Gintama: Jump Festa 2014 Special