Why do I think that?:

Popipa + Hello Happy World + Idol = Pastel Pallettes

Popipa + Afterglow = Roselia

Roselia + Pastel Pallettes + Elegant Violin = Morfonica

Roselia + Afterglow + DJ = R.A.S

Popipa + Overexcited Smile Happiness = Hello Happy World

Roselia + Rock = Afterglow

Hello Happy World + Stars = Popipa