The idol group Keyakizaka46, a branch of Japan's top-selling girl band AKB48, has sparked outrage on social media over their Halloween costume, which resembled the uniform worn by Nazi SS officers before and during World War II.

During a show Oct. 22 at Yokohama Arena titled "Perfect Halloween 2016," the troupe, which ranges in age from girls of 15 to young women of 21, wore black one-piece dresses obviously inspired by military uniforms. Each one featured two rows of buttons on the abdomen, a cape and a peaked hat with a bird emblem that resembles the Nazi eagle. Many social media users criticized it as being "unacceptable," with some posting pictures comparing the band with the Nazi Waffen-SS.

On Monday, Twitter user Takashi Sawanoi (@sawachan42) tweeted "(It's) out!" while user @batayanF3 wrote: "Just because you didn't know or because you don't praise Nazis doesn't mean you can do these kinds of things. It's unforgivable considering how influential they are as talents."