I know thank SQ is not a SkyTeam partner but since you have AMEX points, if you can transfer that 2 J class one-way from LAX-NRT comes out 131,750 KrisFlyer miles
+ USD 107.20 if you book online since there is a 15% redemption discount (65,875+USD 53.60 per person) which is okay. My only tip is to not transfer more than the miles required since they expire after 3 years regardless.
The only Skyteam member that would come close to a Japan redemption would be Korean Air.