All Nippon Airways Mileage Club - Flying EU-US via Japan?

I'd like to buy a ticket from anywhere in Europe to (ideally) West Coast of USA and fly via Japan. I understand that this will be more expensive than 'direct' routing, but I cannot get such trip price anything close to reasonable. (I am looking at business class)

Does anybody know about existing product where you can fly EU-NRT-US-EU in non-full-Y/full-J fare? I checked out RTWs but they are too expensive...

What is "too expensive"? It sounds to me like you are essentially trying to fly literally around the world, in which case RTW tickets are likely cheaper than most other options.

I know that SQ has (or at least used to have) some good RTW deals that are not published on their website, but you'd have to go over to the SQ board and ask the guys there about it because I've never done it and am not an expert. With that, you could do something like FRA-SIN-NRT-LAX, ground transport in the US, JFK-FRA, if I remember correctly.

On vayama.com, the absolute cheapest J fare I found that generally fits your description is $9450, which is much higher than the SQ RTW prices I've heard quoted before.

Half of round trip EU-SFO or EU-NRT can be bought for about $2000, therefore a simple ticket is priced ~$4000. However all fares that fly the opposite direction are full C and cost like $8000 instead of $2000.
Unfortunately it seems there is not a single fare that allows to fly the long way and is reasonable (<$4000).

At this moment it seems that cheapest is a RTW from Prague which costs something like $6000++ (*A)

Only other advice is to try doing your NRT - US leg ex-Asia instead of ex-Japan. In other words, get a one way EU - Seoul/Taipei/etc ticket, and then buy a one way Seoul/Taipei/etc - US ticket that connects in NRT. You'll save loads just by starting the journey in Asia, even if you're dealing with full fare.

Ex-NRT fares tend to be higher than just about any other departure region when you are looking at one way and full fare options.

Perfect example of this, from my own experience: looking at unrestricted one way Y to SFO on NH in August, ex-NRT is ~$5000, but ex-ICN is $1600. Bit of a difference, eh?

EDIT:

I gotta say though, considering how much you're flying, $6000 or so for J seems pretty damn good. You intend to come all the way back to Europe, right?