She also needs to take some Japanese classes so she can actually reply in press conferences and talk to her family. Either that or finally admit she does not like Japan, isn't interested in having any relation with the country or that side of the family and that it was all a big publicity stunt by her father/managers to make more money. It must be horribly mentally exhausting having to pretend to have a connection to a country whose language you can't speak.
She claims not to speak it, but she probably does, just not as well as "some" people would like.
There was a story about how she was playing in a tournament with other Japanese youngsters, and they made a comment about her with her standing right there.
She might not like speaking, and she might feel like she can speak it well enough for an interview, but it doesn't mean she doesn't speak any Japanese.