It's terribly clever. You can slide your iPhone 5 inside it, slip it into your back pocket and it looks like you have a gun there. Who wouldn't want one of those?
In the US, however, this product isn't enjoying universal admiration. For example, the Ocean County Prosecutor's Office in New Jersey offered this warning on Facebook: "Please folks -- this cell phone case is not a cool product or a good idea. A police officers job is hard enough, without having to make a split second decision in the dark of night when someone decides without thinking to pull this out while stopped for a motor vehicle violation. What do you think?"
There's even an app that allows you to pretend that the gun barrel continues across your iPhone's screen. And it costs a mere $49.
Many of the Facebook commenters agreed with the prosecutor's office. I have contacted the Japan Trend Shop to ask whether the site believes its product is dangerous. I will update, should I hear.
However, the site's blurb does offer this helpful reassurance: "Don't worry, you can't actually shoot anyone!"