If I understand correctly, your constraints are that you want a morning arrival and to be in premium economy for as much as possible. I see 3 main options:
1. AA BNA-LAX-HND with LAX-HND in premium economy, then HND-OKA on JAL, with BNA-LAX and HND-OKA in regular economy
2. DL BNA-ATL-HND all in premium economy, then an overnight layover in Tokyo, then HND-OKA the next morning on JAL or ANA
3. UA BNA-SFO in economy, then SFO-HND-OKA on ANA with SFO-HND in premium economy
Between these, the price is roughly comparable. Speaking from a personal perspective, I would not take the Delta option, given the 16 hour overnight layover followed by a 6 am flight. Between LAX-HND on AA premium economy or SFO-HND on ANA premium economy, I would definitely pick ANA. The only downside is the 5 hour flight from BNA to SFO in regular economy, but it will all come down to your personal preferences.