Looking at options to get home from Vietnam. Would I be safe booking separate award tickets on ANA and JL like below? Any issues trying to depart from SGN with separate tickets through Tokyo? I will not check any bags. Thank you!

NH 829 Business Class SGN-HND 6:55 AM Arrival (Lifemiles)
~5 Hour Transit
JL 10 First Class HND-ORD 11:45 AM Depature (AA miles)