Haven't you guys heard the term dox? Ayu was doxed. It's a major problem for many people in our internet generation. Celebrities have their phone numbers and home address leaked regularly. Any public figure really. Many content creators on YouTube have expressed this struggle with having private information published publicly online for all to see. Fans or other individuals coming to their homes at anytime of day or night. It is such an awful problem.
It looks like it finally happened to Ayu.
What that person did is illegal and against the law. At least here in America it is. Their intentions don't matter from a legal perspective. I don't know if Japan has any laws against doxing though.
But Ayu will be okay. She has the means necessary to deal with something like this. She must be at least a little bit shaken up though. I know for me personally, I value my privacy greatly and I hate when it gets infringed upon. So I feel for Ayu at the moment.