I'm a big fan of Sumo Boy. This is not a high end restaurant, but for a strip mall in Mentor, its great. The food is consistently good, the service is always friendly, and the prices are very reasonable. And though it can be a little busy on Friday or Saturday night, we've never had to wait more than a few minutes for a table.
One of my favorite things to get are their version of a bento box, which they call a Sumo Box. Their sushi is consistently good and high quality. They do good teriyaki and tempura. I have to say that while their miso soup is good, the noodle soup bowls are mediocre and a little bland.