I see a $1,455 flight for Jan 8-Apr 24 but it is a hellacious 54hour trip with 3 airlines United, Swiss, ANA Nippon.
Next cheapest is $1,613 for Jan 8-Apr 24 for 34 hours with JetBlue & Cathay Pacific.
I also checked one way from Atlanta-to-Osaka and one way back. Not any cheaper. Also looked at Tokyo and other cities (e.g. he can take a train to Osaka) and not much better.
Not sure if below link will work ...
Google Travel