By Agence France-Presse
Teeny-boppers Keyakizaka46 had sparked anger with their black one-piece dresses and capes, complete with peaked caps bearing a golden bird symbol resembling the Nazi eagle above a swastika, donned at a Halloween concert in Yokohama on October 22.
The Jewish documentation, monitoring and human rights organisation in a statement issued Monday expressed "disgust over the use of Nazi-themed uniforms donned" by the group.
Rabbi Abraham Cooper, the Simon Wiesenthal Center's associate dean, said the display was "inappropriate and deeply offensive" and called for Sony Music Entertainment -- the group's label -- and producer Yasushi Akimoto, to apologise.
"Watching young teens on the stage and in the audience dancing in Nazi-style uniforms causes great distress to the victims of the Nazi genocide," Cooper said.
"We expect better from an international brand like Sony which has caused embarrassment to Japan."
Hours after the statement was issued, Sony Music apologised, blaming its "lack of knowledge in designing costumes that reminded people of Nazi-style uniforms".
"We apologise from the heart for causing unpleasant feelings," the company said in a Japanese-language statement on its website.
"The costumes will never be used again."
Producer Akimoto also posted an apology on the girl band's website.
"I am very sorry for failing to oversee matters as the producer," he said.
Akimoto, also a lyricist, is the mastermind behind the group and many other similar girl bands, most famously AKB48, which consists of a 100-strong pool of girls in their teens and early 20s rotated in and out of the public eye based on their popularity.
Keyakizaka46 have shot to stardom since being formed in 2015 by Akimoto, reaching number one in Japan with their debut single "Silent Majority."
The helium-voiced pop queens are not the first Japanese band to cause offence.
Retro rock band Kishidan angered the Simon Wiesenthal Center in 2011 when they wore a costume the Jewish organisation said resembled a Nazi uniform.
In neighbouring South Korea, girl band Pritz provoked protests two years ago after wearing bright red armbands strikingly similar to the ones Nazi officers wore.
Cooper will travel to Japan this month for the opening of a Holocaust exhibition, the statement said.