Well, I'm Japanese and need Japanese grocery items and this store is conveniently located next to Arai Bakery and so when we go to one, we go to the other.
This is a small grocery, not much of an inventory, but they do have the basics. Need yokan? They have it. Need real negi? They have it, so you don't have to settle for just green onions. They have other produce that you can't find anywhere else. Just be aware that they have very little of it.
Just a little quaint, family-run, sort of convenience grocery store that might fill a few needs, but nothing comprehensive.