A city/neighborhood/area for antiquing in Tokyo?

Way out of my depth on this one.

A relative whose coming to visit is very into antiques/antiquing. My knowledge of the hobby extends as far as basically knowing the word “Antiquing” (thanks Bender/Futurama)

I know Tokyo neighborhoods tend to segment into business style districts – Is there an area with a higher concentration of antique businesses/stores? My relative isn’t super mobile, so I’d like to bring them somewhere and let them walk between stores/take their time.

Would greatly appreciate any insight.