I want to recommend "Little Tokyo Restaurant" in San Dimas.
I've been to so many Sushi restaurants all over the Los Angeles area including downtown, Pasadena, Santa Monica, South Bay, Beverly Hills, Irvine, Monterey Park, etc., but this Little Tokyo Restaurant is a something special to me. Tommy makes delicious sushi. Ask the repeaters at the sushi bar for more details.
Believe me, I am a Japanese and loves sushi. you should try this one at least once. It might be a little longer drive for most of you, but it is a worthwile tasting the best.
Link: http://maps.yahoo.com/py/maps.py?BFCa... E. BONITA AVENUE&csz=SAN DIMAS%2C+CA&Country=us&Get%A0Map=Get+Map