Hiragino is distributed by SCREEN (formerly Dainippon Screen) and licensed by Apple. If you are using the font for commercial work on a PC, you must purchase the Hiragino Kaku Gothic pack. Downloading a .ttf from a font aggregator is piracy.
Hiragino is a proprietary font. You cannot legally download it for free from random websites.
Even after your Hiragino Sans W9 install, things can go wrong. hiragino sans w9 install
How do you know the Hiragino Sans W9 install worked?
Common Failure Signs:
You need the actual font file (Hiragino Sans W9.otf or .ttf).
If you have a legal copy:
Once installed, you need to use it correctly.