I've had this right at one point in the past on one machine with a certain font type at a particular font size, but I can't seem to get it right again.
Look e.g. at how my org mode tables look once I add Japanese characters. Here are two examples using fonts that were supposed to align properly (I read somewhere).
Help!
This is version
GNU Emacs 24.4.1 (x86_64-pc-linux-gnu, GTK+ Version 3.14.5) of 2014-12-10 on gaia, modified by Debian
Edit A copy-and-pasteable version of a bunch of alignment problems for anyone who wants to try themselves:
| a 漢字 | |
| b はどう | |
| f デショウ a | |
| ハーフ | |
| whole | |
| half | |
| ○ | |