Supermarket advertising low prices.
In Arakawaoki next to Toys'R'Us. They have good sushi, yaki-tori, futo-maki, tempura shrimp, etc. These go on sale (up to half off) around 6:30-7:00pm. Good strategy: get it the store a little earlier and stock up on what you want in your cart (to avoid the mad rush after the discounts start). Then they'll make an announcement that things are going on sale and clerks will start putting discount stickers on the packages. You can bring your items to the clerks and they'll tag them for you. Don't get greedy!