I'm Japanese, so let me give you the best guide on what to buy! This is everything I bought in Japan during my trip in fall/winter. I bought most of these things in Tokyo, but they can certainly be found in Osaka too. I also included a guide to all the best shopping spots so you're not overwhelmed.
CHAPTERS
00:00 Intro
00:50 What local girlies are buying
03:27 What’s worth it?!
05:18 Makeup I’m wearing
06:50 Sunscreen
07:12 Skincare
08:10 Stationary
08:55 Clothes
10:40 Electronics, Hair removal machine
12:06 Souvenirs
13:19 Guide to the BEST shops in Tokyo