Gal*Gun: Double Peace is a game about shooting schoolgirls with your love. It is not for everyone, and especially not for Everyone with a capital E, as shown on the back of the physical Vita release of the game.
Picture via Wario64.
Caught by Wario64 on Twitter (via Destructoid) and corroberated by other early recipients, while the front of the Vita version proudly displays the M rating assigned to it by the ESRB for "Sexual Themes", the back of the box tells another story. It's like a ratings mullet.
Twitter's Jamie Bravo has both sides of the story.
— Jaime Bravo (@KingFrostFive) July 31, 2016
If I had to guess, and I do as North American Gal*Gun publisher PQube hasn't responded to my inquiry yet, I'd say this was somebody's joke that accidentally got sent to the printer. I'd also say the eSRB is not going to be happy with it, and that anyone who has gotten a copy with the botched rating should hold onto it, as those won't be around for long.