Takesushi has a decent reputation and is definitely the closest geographically.
Hiro Sushi at 171 King East is highly recommended and within reasonable walking distance.
Also, there is Nami at 55 Adelaide East. http://www.namirestaurant.ca.
171 King St E, Toronto, ON M5A1J4, CA
55 Adelaide St E, Toronto, ON M5C1K6, CA