OS trip advice
Japan itself is pretty daunting when you first arrive if you haven’t done any/many asian countries before. Seeing as she as gone to Indonesia by herself before, she shouldn’t have too many issues with Japan.
Might be best to book a transfer from the airport to Hakuba anyways. I jumped on at the airport and they took us all the way on the bus. Might not be as awesome as getting on a bullet train. But I didn’t have to try and get directions the second I got off the train.
Especially handy if you arrive in Narita late at night. Lugging board bags through crowded Tokyo trains is not fun.
I can’t speak for Niseko but Hakuba is going to be great for Low intermediates ski/boarders, So many empty runs, wide flat-ish groomers. (easy Blue runs - which happen to be red in Japan) Some resorts to tick off your list would be Goryuu/47, Happo One, Iwatake and Tsugaike. I wouldn’t bother with Cortina and Norikura unless you fancy a bit of off piste treed runs. It’s even possible to get a bus from Hakuba to Myoko (pretty sure there’s on to Nozawa too) But you’re gonna have loads of variety in the Hakuba area already.