This supermarket is nice, but really expensive and does not have so many vegan foods. In fact, there are way too much meat and dairy.
However, their deli dishes are really affordable. They have several kinds of bento, soups and a curry that are labelled 'for vegetarian' (but it seems they all these options are vegan). They also have several kinds of fresh vegetables. I had a bento with a chunk of tempura and rice, only 500yen.
If you come later in the afternoon, most of the deli food might be gone. I came at 6pm and there wasn't much left.
You can eat in or take out. There is a microwave to heat your food and complimentary tea.
All in all, it's a nice place. The food is fresh and tasty, and I am always happy to find vegan food in Japan. The prices in the deli are also OK.
Cons: The supermarket is expensive, Not many vegan foods in the supermarket, No ingredients in English