Shinokitazawa located in Setagaya, Tokyo. Shimokitazawa has been famous known by variety individual vintage fashion shops, cafes, bars etc. There aren't only Harajuku, Shibuya that that popular for shopping and entertainment in Tokyo. If you want to experience another side of Tokyo, Shimokitazawa is the place. The streets are full of vintage retailers, individual coffee shops, you can even enjoy a live music there.
I recommended a super old and tiny shop in front of Muji that closer to the station. It owned by an old man, he is so stylish and cool. The shop sales everything, from home display to clothing etc. I found some interesting pieces I would like to buy if I have my own house in Tokyo. If you planning to buy your own house or stay long term in Tokyo. You will found some real vintage stuff in his shop that suitable for you house.
Besides that old man's shop, there is a big indoor area that including lots of different individual shops. There is one that you can rent a box inside the shop in order to sell things that made by yourself. Also some very stylish vintage shops inside, but the price is kind of expensive.
Close to Shimokitazawa, there are lots of cool places that you can visit. I like Setagaya area in Tokyo. It doesn't like Roppongi, Omotesando or Azabu that full of luxury chain shops, as well as full of people. Setagaya area has many small streets that you can actually experience a different side of Tokyo. If people first time travel to Tokyo, I definitely will recommend this area, especially for people who like explore the different part of the city.
You can access there by taking Sobu Line or underground, depends on which part of you Tokyo you live. Shimokitazawa has both north and east exits, I recommend don't miss any part of it. If you plan a day there, it is good to arrive Shimokitazawa around lunch time. Try some lunch menu at local cafe or restaurant. I have been there twice, the first time I totally missed east part of it (I can't figure out which part is north or east.). The second time. I found there is a cheap secondhand shop by that area called Stick Out. All the clothes there are 700 Yen, what an amazing place. The shop is not that big, so it always full of people during the weekend. However, I think this might be the only cheap place to get second hand or vintage clothes in Shimokitazawa. My personal opinion, most of those individual shops there with "Vintage" or "Retro" tag, the price sometimes as same as new clothes, some of them even cost more.
So if you are thinking I am not a fan of vintage shop, does Shimokitazawa still a good place for me to travel? Yes! That area has so many cool local shops, izakayas (Japanese bar), cafes etc. You can easily find a nice cafe, relax for a whole day.