I used to spend a fair bit on books at Kinokuniya monthly. The expenditure was considerable.
I had done a reality check and also some comparisons a few years ago. I thought the money could be better spent on books from Amazon and Books Depository. The prices at Kinokuniya was and is far too high, and can be double or triple the recommended listed price. I could get double or triple the volume of books for the same amount of money I had spent.
From then, I have reduced my purchases at Kinokuniya to the odd stationery item like a pigment ink technical pen or paint brush and a few magazines annually. Since then, I have been buying from Amazon. One has to be realistic.