Koto is an average hibachi restaurant with higher than average prices. The food preparation show is fun if you have never experienced hibachi before, but I can't say that it was all that spectacular. There are a number of food options for lacto-ovo vegetarians. That said, it's definitely worth mentioning that you're vegetarian so that the hibachi chef will hold off on grilling the meat dishes until after the vegetable dishes are finished.
As a vegan, I was pretty appalled that my strawberry daiquiri automatically came with whipped cream and my vegetable hibachi dinner was made with a large slab of butter. The waiter was willing to replace my daiquiri with a dairy-free version, but nothing could be done about the butter in the hibachi dinner. I realize that plenty of restaurants probably throw butter into my otherwise vegan meals and I unknowingly end up consuming it, but it was frustrating to watch as large slabs of butter were added to my food against my will. If it hadn't been for the fact that this was my friends' wedding reception, I probably would have left.
That said, the service was excellent and the chefs tried to be as accommodating of my diet as possible (they even cooked my meal first, so that there would be no cross-contamination with meat), so I've decided to give Koto a rating of "fair" instead of "terrible."