I have always been a fan of Mitsuwa Marketplace, but the prices have always been quite steep for me. I now only go there when I want to have some cheap ramen from the food court. Not too far away from Mitsuwa was a marketplace called Murakai, but it has since been closed. In replacement of Murakai is Tokyo Central, my new favorite Japanese marketplace.
Unlike Mitsuwa, Tokyo Central does not have a designated food court with varying restaurants in it. Instead, it has a buffet (think Whole Foods), a large selection of fresh sushi, and occasionally, they host varying food events where they set up small stalls at the front of the store testing new drinks or food to sell in the store. Aside from that, Tokyo Central sells a variety of items from house ware, fresh produce, seafood and meat, snacks, beauty products and much much more. You can also sign up for their membership card which allows you to earn points towards future discounts.
Next to Tokyo Central is a Book Off (used books and electronics store) where you can fulfill all of your reading and nostalgic electronic needs. Overall, I absolutely love this marketplace and highly recommend it to anyone looking to try new snacks or to get some Japanese food and goodies!