The lawsuit claims that Forever 21 offered products in its stores that were "virtually indistinguishable" from Harajuku products. In turn, Stefani's company has "suffered and continues to suffer damage to its business reputation."

Stefani's lawsuit states that Forever 21 "changed a couple of words in the Heart/Box Trademark, which are inconspicuous and likely to go unnoticed by a consumer." The allegedly ripped off Harajuku Lovers products use a Heart/Box logo with Japanese script that says "Harajuku Lovers." In the Forever 21 version, the Heart/Box with Japanese script said "Forever Love."

Forever 21 was also sued in March by Diane von Furstenberg. The veteran designer claimed that the company stole the design for her $325 "Cerisier" dress to create their $32 "Sabrina" dress. Forever 21 allegedly copied the entire dress including the pattern, colors and measurements.

Many websites have documented the chain's knock-offs, notably Fashionista.com. That site has found instances of Forever 21 offering nearly identical products to those made by Foley + Corinna, Proenza Schouler for Target, Anna Sui and other brands.