Nigiriya is a definite "must visit" for sushi lovers visiting the Leaside area - it's a hidden gem. I'm a veggie maki roll fan because of my allergies to seafood and I have NEVER had a simple kappa (cucumber) maki roll make me say "Mmm!" the way I did when I took my first bite into Nigiriya's!
The small, humble looking restaurant gets my 5 stars for the friendliness, cleanliness, and especially the quality of the food that is offered at a reasonable (but to some, a touch on high side) price.
A caution about the hours. I heard they open for lunch but I am not sure exactly when, then the restaurant re-opens at 4:30pm until 9pm, Tuesday-Sunday.