Really small but extremely delicious restaurant with a variety of seafood teishoku (set meal). You will usually only see locals and nearby office workers, which is a very good sign of a delicious restaurant. There is no English menu, so definitely use Google Translate. Some of the dish names are handwritten and may not even be translated by Google Translate, so you can check Google Maps photos of food and show the waitress the photo of the dish you want to order.
It is pretty hard to find as it is located on the underground level of a huge complex so I included as many photos of its entrance as possible.
Enter the building here📍 after riding down the escalator
go straight a little bit after entering the building
the restaurant should be on the left