Found this place on Happy Cow, so glad I did.
So far it's the best food I've had this trip.
I'm terrible with reading and understanding spoken Japanese, but luckily the owner(I think it's the owner, she is always there) is very patient and will translate the menu for me and is very friendly.
They do take away as well which is nice since there is a beautiful park just around the block.
Amazing drink selection, alcohol, and pages of vegetarian food and snacks.
I'm not totally sure of the hours, but even during Golden Week they are open at least until 21:00.
Quality and variety of the food is great as well.
Very good vibe there also, fun decorations.

This place is a little gem in southern Tokyo. The food was delicious (particularly the entrees) and the owner (I think) was very friendly and welcoming. She had translated about half of the menu into English (so it will probably be all translated by the time you read this), and she patiently translated and explained the other half to us. The Hawaiian themed interior is simple and pleasant, making this place a good choice for enjoying a meal in Tokyo. It's quite a small place so it's probably worth booking ahead.