Usually Delta and united airlines around 550-750 to fly to NRT (return). Take united if you have Krisflyer to earn miles.
Now Ana and JAL having sky deals. I bought Ana to NRT (return) for 610. Promotion is till 31 mar. For this deal, you can choose between Tokyo, Osaka, Nagoya ot Fukuoka. Sapporo and some other cities cost a little more (around 800). Ana is under star alliance so can get the miles as well.
I also checked MAS and SIN to NRT or KIX (return) cost $475. I flew on MAS to Kansai before, they are not bad, just that you have to transit at KL.