This might be the slowest Green Grotto I've ever been to. I wanted something quick and easy while waiting for someone in this plaza.
I went on a Saturday afternoon and was could sit anywhere I wanted. There was one group of teenagers and maybe 2-3 tables of two people. Needless to say, it was pretty empty so I don't know why it took so long. Perhaps because I ordered a dish with rice. I waited about 30-40 minutes for it. Maybe they had no rice and had to make it just for my order. I would've appreciated a warning though - and I can't imagine how long the wait would've been if they WERE busy.
The popcorn is always a nice touch and I snacked on that while I waited. I also got a takoyaki because my actual dish took forever. The takoyaki came out in maybe 10-15 minutes.
The food and service are both mediocre. I didn't order any drinks so I can't comment on that. I wouldn't return as there are other similar cafes in the area and if I wanted to go to a Green Grotto, I would head to another location.