It's a bit of a trek from where I live but I ALWAYS make it a point to come up here, especially when I'm making a Japanese or Korean dish and I need the ingredients. PAT carries Japanese/ Korean items that even the big Chinese supermarkets like T&T do not have. PAT has a wide selection and I am particularly fond of their ready made/ ready marinated foods, which is quite typical of a Korean supermarket. Definitely the biggest and the best in the area if you're looking for Korean/ Japanese ingredients! I always pick up my natto beans, bibimbap ingredients, marinated bulgogi, hondashi, etc. here. Not as cost-effective as your typical Asian supermarket like the ones down on Spadina, but it's a great one stop shop if you're looking to make specific dishes that require difficult to find ingredients. Good meats, noodles and condiments selection. Don't expect great service... This is an in and out kind of place and who really goes to a supermarket for service anyway?
As everyone has said already, don't forget to stop by Kevin's Taiyaki. There's a reason why the custard filled one is 25c more ;).