Take an Asian carrier, even if you have to go via NRT.

If you're flying out of ORD, you'll have to make a stop anyway to go via UA. Go ORD-NRT on ANA, then take a domestic flight to KIX (or to ITM if your destination really is Osaka and not one of the nearby cities, such as Kyoto.)

Once you've taken an Asian airline, you'll understand why many of us greatly prefer them.