But my favorite place for Sushi in all of Las Vegas (trust me I'm picky) is Shibuya inside of the MGM. I know you are tying to avoid hotels, but this place is to die for!

I think you are looking for

these places; which are all very good and in no particular order some of the best in Vegas. You should call ahead since reservations may me needed. ENJOY!

Raku and Kabuto are in the same area. Soho is not on Spring Mountain, but has some of the best & freshest sushi in Vegas.

1. Raku Japanese - 5030 W. Spring Mountain Rd. #2
TEL:702-367-3511 - Open 6pm-3am / Closed Sunday  

2. Kabuto   - 5040 Spring Mountain Rd. #4 - (702) 676-1044 - Hours: Mon-Sat 6 pm - 11 pm

3. Soho Japanese Rest.
7377 S Jones Blvd. (702) 776-7778  
Hours:
Mon-Fri 11 am - 2 pm
Mon-Fri 5 pm - 9 pm
Sat-Sun 5 pm - 10 p