Hi Yutaka,
my apologies. I assumed images were enough.
my point is simple. EE currently supports only ASCII view in HEX mode, therefore only ASCII character can be displayed side by side HEX. I suggest an enhancement on this, i.e. to support codepages or unicode view side by side HEX mode.
I posted a screenshot of another editor (Madedit) that I think does well on this to illustrate my idea. As you can see, Madedit displays multi-bytes characters side by side HEX, while in EE same characters were replaced by dots.