Ironic that it's considered an "Erika cosplay" when the clothes were presumably Jessica's to begin with.

Taking into consideration that we never see Jessica in her old dress (as of ep5), and it's essentially Erika's main outfit in the series, it ought to be considered hers.

I mean, if someone else wore it you wouldn't tag it Ushiromiya_Jessica_(cosplay), would you? It would still be an Erika cosplay.