Within Shinjuku's own Shin-Okubo, which is widely dubbed as its "Korean Town", the Seoul Ichiba market offers a large variety of Korean food supplies. They actually would not allow any photography inside the market itself but it goes without saying that this is the best place to get high quality Korean foods in the area. Both freshly cooked and ready to order if you're looking for a "to go" meal or prepackaged and ready to be integrated into your next meal at home.
As an English speaker and Japanese as a second language learner, the multitude of Korean characters are partnered with their Japanese cousins but there is no English in sight. Many visitors may have to rely on the appearances of the food but thankfully, everything I saw looked delicious.
The family in Japan I’m staying with are huge fans of kimchi and this place delivers on tasty variations. They keep having me go back for the garlic variety but there are many to choose from and most have samples readily available. Along the edge of the open refrigerators are servers and cooks handing out cooked meals and more samples. Expect to be delighted by the selections and indulged in taste testing.
Getting there is quick but the market can be easily missed if you get caught up in the crowd. From the Yamanote line, get off at Shin-Okubo station. There is only one exit so once you make it onto the street head right and make your way through the bustling street until you come to the local shrine entrance. The market is immediately after it on the right hand side.
A word of warning before setting out: the market has some tight spaces and wading through the crowds within the building can be an exercise of one’s patience. I always feel like I’m in someone’s way when I’m there so I don’t usually dawdle too long in one place. Your experience may vary of course. Also, the surrounding area seemingly has a never ending stream of people flowing through both sides of the streets. For some, it may be easy to get overwhelmed. That being said, don’t let that deter you from making the trip. Enter and you shall leave with something tasty.