Mitsuwa Marketplace in Costa Mesa, (CA) is one of my favorite places to go! From the delectable Pickle Sushi and packaged Tsukemono (literally translated: "pickled things") in the main market to the adorable J-Style store which carries anything from Totoro plush dolls to miniscule poodle-shaped nail-stickers, you will be impressed! Try the Tempura Udon from Sanuki Sandou, and go check out the awesome selections of Japanese pens in the Sanseido Bookstore! From tiny food-shaped erasers to great deals on Nigiri Unfiltered Sake, any Japanophile will love this one-stop wonderland of Japanese creations large and small!
(I have been to several Mitsuwa Marketplaces around Southern California, and the Costa Mesa store is undoubtedly the king of them all!- in a pinch the others will work for cooking ingredients, but for the full experience, go the extra mile and head to the Costa Mesa store!)
Here is a link to the Marketplace, it's easy to find, located just off Bristol Street, on Paularino Drive, just across the street from South Coast Plaza!