Gal Gun: Double Peace isn’t out until tomorrow in North America, but early copies have already been delivered to buyers, revealing a misprint on the PlayStation Vita version.
As you can see in the above image, the Vita version of Gal Gun is labelled as ‘M for Mature’ on the front of the box. On the back, however, it’s labelled as ‘E for Everyone’ for “sexual content.”
According to the ESRB’s official ratings description, Gal Gun is rated ‘M for Mature’ due to sexual themes. Here’s the full reason why it’s rated Mature:

This is an adventure game in which players assume the role of a young boy named Hodai who has been shot by Cupid and must find his true love. Players move through levels, fend off female characters, and help several heroines through interactive scenes. These interactive scenes often depict female characters wearing revealing outfits (e.g., lingerie) in sexually suggestive positions (e.g., stuck in windows, arched on the ground, restrained by a tentacle monster). Players can activate a “Doki-Doki” mode, in which a 360-degree view of female characters is depicted; players attempt to bring characters (clothed) into a state of euphoria by using a cursor to click on various body parts (e.g., face, legs, chest). Sexual moaning sounds can sometimes be heard. The dialogue also contains sexual innuendo and provocative material (e.g., ?Are you sure you can pull out in time"...