Jalanka is a small Japanese supermarket in Colombo 8. They have a lot of good and reasonably priced sauces, noodles and imported Japanese items.
Jalanka is a long-running Japanese food and supplies store. You can get everything from Ramen noodles to slippers to rice to industrial size packs of pickled ginger. We tried some Ramen (instant noodles), a Rs. 100 pack of instant miso soup and some frozen yoghurt jelly treats. They're all quite good.
Jalanka also has a good selection of sauces, oils, preserves and condiments. If you know what you're looking for it's an excellent resource and - even if you don't - there's a lot of interesting stuff to try.
They also have a fair amount of non-food items (slippers, bowls, etc) if you're looking for small gifts.
They have Ramen noodles.