Try comparing it using a JP->US reshipping service and small Muji purchases in US seem almost reasonable. Especially on liquids which can be heavier for the spatial volume**. Muji Yurakucho also offers tax free exemptions at a separate counter. Muji To Go Kitte offers more of the travel goods (am also told they have tax free).

JINS eyewear is less expensive in Japan and offers tax free. The supplemental lenses cost less in Japan, too. JINS US has western fit and asian fit frames which may not be immediately obvious. JINS JP has larger selection/variety of asian fit which can have a larger nose bridge (so it sits further from the face if you're used to western fit). JINS US receipt is easier to submit for US vision insurance reimbursement if you're eligible. JINS in Yodobashi Akihabara had an English speaking staffer, as did Zoff at Marui Yurakucho and a few other shops around Ginza and Akihbara. Receipts are largely in Japanese.

Uniqlo US on a good sale can be cheaper than JP. Uniqlo US doesn't have the full JP clothing line, though, and GU is even less expensive if you're ok with Asian fit.

** Drugstore skincare & cosmetics can be a good deal via Amazon.co.jp, Donki, and electronic stores but do account for the volume, weight, and use by date. Some skincare only costs $4/5 more via Amazon Prime US or eBay and you won't be risking leakage in your checked luggage or stockpiling past a good freshness date. As far as whiskey, there's a thread for that https://www.flyertalk.com/forum/japa...e-whiskey.html