Can't tell you about Lakeshore or High Park, but here's a list for North York...I live in the area and is a sashimi lover ;)
Hiro Sushi - 5213 Yonge (North York Centre)
Ichiban Fish House - 15 Spring Garden Avenue (near Yonge/Sheppard)
Sapporo Sushi - 5469 Yonge (near Yonge/Finch)
Those are 3...