Shibuya's newest mall (opened in 2019) has eight floors of fashion, beauty and lifestyle boutiques (and more floors for restaurants, cafes and gourmet food shops). There's a little bit of everything: international and Japanese brands, high-end designer goods and solid staples, plus small branches of popular shops like Tokyu Hands and Tsutaya Books.
Shibuya Sky is on the top, so odds are you're visiting anyway.