The next volume of One-Man Punch include an OVA

http://latest.thechromenews.com/2016/01/21/the-next-volume-of-one-man-punch-include-an-ova/

For those who purchase the upcoming release on DVD or Blu-Ray Man One-Punch will be a big surprise.
The next release in format DVD / Blu-Ray of one punch man include some pretty special extras, including an OVA.