If you do not want to buy a license (which costs roughly $100–$200), here is how to access Hiragino Sans W7 for free legally.
If you need a free font with a similar neutral Japanese sans feel, consider legally free/open-source Japanese sans families (they won’t be identical but can substitute): Hiragino Sans W7 Font Free Download
Some Japanese font distributors (e.g., Typekit or Morisawa) offer a time-limited trial of Hiragino Sans. Search for "Hiragino Sans trial SCREEN". You get full access to W7 for 7 days for evaluation. If you do not want to buy a
Yes, but not for free. Since Windows does not include Hiragino by default, you have three options: Yes, but not for free
If you need a similar font for free on Windows immediately, skip to the alternatives section below.