First of all, the hiragana "no" is always Japanese, not Chinese, not Korean. The CJK unification is only about han characters (in Japanese, that's kanji).
As for maths, there are usually markers to indicate we are in an equation, which makes sense because Unicode is not powerful enough for this : fractions, integrals, matrices, etc... cannot be rendered with just code points. So in this case Unicode provide the characters (roman and geek letters, numbers, mathematical symbols, the hiragana "no", etc...) and a higher level language (like MathML or LaTeX) deal with the structure. Because of this, Unicode doesn't have to dedicate a special page for mathematical version of regular characters : the software can easily differentiate. If it is MathML / LaTeX "$" block, render it with the math font, otherwise, use the regular font.