I just came back from Japan. Let me share with you.
For clothing, you can go to some Factory Outlets or some remote shopping centres.
For me, I went to Factory Outlets in Yokohama. It is called "Yokohama Bayside Marina". There are Nike, ABC Mart (shoe shop), Coach, Seiko, Indivi... Before I go there, I’m afraid that I don’t have anything to buy from there. But I bought two handbags and some sports clothings there. The handbag is around $300 HK dollar only. My family also bought some sport items. I spent lots of time and $$ there.
I also went to Daiba (台場). There are some shopping mall too. I bought 2 pairs of shoes and the brand name is called "Jelly Beans". One pair of shoes is on sales and it costss $HK280 around and the other one is new arrival and it is only $5xx. These two pairs of shoes are made in Japan. I think the price is reasonable. I also know that the shop of "Jelly Beans" in Mitsubishi in Shinjuku. However, I can't see any sales items in this shop.
I also bought some clothing for my kid. It's in Takashimaya in Shinjuku. It's on sales too. I bought one T-shirt, one short and one dress (they are made of wool and made in Japan). It is just around HKD7xx. I can’t imagine that I can buy such kind of products in HK with this price.