How to disable anti-aliasing in Notepad++ 6.7.9.2

Japanese text … does not appear anti-aliased in my browser

Windows doesn't anti-alias fonts below a certain size - I believe this is font specific. Try a different font or try increasing the text size (Ctrl++ in many browsers)

is there a way to ensure a website of my own creation displays anti-aliased Japanese text?

There is no sensible way to achieve this. Your website might be viewed by PCs running a variety of different operating systems with a variety of browsers. Consider phones, pads, tablets, netbooks, TVs and other hardware platforms.

You could pre-render the text as graphics images but this is troublesome to achieve in a way that is readable on both phones and dual-24" screens. It also means your text won't get indexed by search engines and so is likely to rank lower in searches.

Your could use Flash but many of the same disadvantages apply. Not all platforms support Flash and some people disable it.

Usually xterm does not apply antialiasing to fonts. However, I think some windowmanagers like compiz generally apply antialias to windows, hence your problem would be your window manager, not your terminal emulator. Try checking your window manager for antialiasing and try disabling it.