I do not know about Japan, I only know I have a cousin who is married there.
. But here are her grandparents from both her mother and fathers side. They stayed here when she and her parents left when she was 2. After that her parents separated. Every year in the summer she comes back to see her grandparents. Some years ago she even comes hare skiing and snowboarding (there are pictures). Some lucky fans even post pictures when they see her walking the streets, but I have never had that luck. Anyway, most this I know from video interviews. I am not very keen on believing printed ones as they may not be exactly what she said, unless it is a more popular magazine with real interview. I believe what she says personally. When she comes back she stays very low key and never announces it.