Do you know if a passenger will have lounge access in Narita for following transit? From what i search, if a passenger arrived on business class on ANA operated flight, she can access ANA lounge. Not sure on below case

My mom is travelling on reward ticket for following route

RDU --> EWR --> NRT --> HAN
RDU --> EWR (first operated by United Airline)
EWR --> NRT (business operated by United Airline)
NRT --> HAN (economy operated by ANA)


Many thanks.