Manpuku is one of my favourite lunch spots in the area. Located right across OCAD, the restaurant is hidden inside a foodcourt. Offering a variety of Japanese options, I would describe their menu as simple homestyle cooking.
The portions are decent for the price you pay, but if you are really hungry - I would probably order 2 items. With most dishes averaging in the $5-$7 range, you really can't go wrong. My favourite items on the menu are the beef niku udon, curry don and takoyaki. A must try if you are in the area.