It would be useful to know which font or fonts are being used to type the characters, before they're displayed in MS Mincho.
I've found only three fonts that include the zodiac symbols: Arial Unicode MS, MS Mincho, and Wingdings. Even Lucida Sans Unicode doesn't include them. I’ll rule out Wingdings because it puts the zodiac signs in a different range
of character numbers than do the other two. Thus I’ll guess that you were entering the symbols in Arial Unicode MS, but that font isn't properly installed, so Mincho is substituted.
The page at
http://www.microsoft.com/typography/fonts/font.aspx?FMID=1081 —although it isn't always reliable—indicates that Arial Unicode MS ships with Office 2007 but not with any version of Windows. I believe that's one of the “Additional Fonts” that have to be selected
in the Office installer's Custom setup in order to install. As you say your OS is Windows 10 Tech Preview, maybe Office 2007 wasn't completely installed there. That might also account for the substitution in the web browsers on your computer; does displaying
the same web page in any browser on another computer have the problem?
My main suggestion would be to try uninstalling and reinstalling the font that you're trying to use, whether it's Arial Unicode MS or something else. As a workaround, use the characters from Wingdings instead; that's an old font
that comes with all versions of Windows and should be available everywhere.
