2.) IME toolbar with English in effect (default):

4.) IME language selection menu:

5.) IME Direct Input method (default):
6.) Click on IME's input method indicator:

6.3) IME indicating hiragana input with あ:

8) Word recognized. IME candidate list appears:

9.1-2) [Space] or [arrow] to select candidate:

9.1-2) Candidate chosen. List and zig-zag disappear:

Sample Document with 日本語 and 英語 (Japanese and English)

HTML requires no language-switching (but indications should be given for accessibility). I can mix English and 日本語 at will. HTML 5 even has facilites for ruby text, a way to indicate pronunciation for 漢字 (kanji) in 平仮名 (hiragana, phonetic syllables) to help children and new learners with unfamiliar 漢字. (Hiragana are also used for particles and many short words and common phrases; a companion katakana does the same for foreign words, to distinguish them.) There are approximately 1800 漢字 in common use, though there are rare Chinese dictionaries with over 50,000 漢字, so it's helpful for adults, too!

こんにちは！ Example of ruby text: 日本語(にほんご).

Typing 日本語 with Input Method Editor (IME)

1. Open the application in which you wish to type. Ensure it has focus.
2. Locate IME in your taskbar; it displays the current language in effect for the application with focus. (You can have multiple applications open with different languages in effect in each.)
3. Click on the language indicator (in this case, "ENG").
4. Select a language, such as "Japanese". (The indicator changes to a black-and-white icon.)
5. To the left of the language, the current input method is now displayed. For Japanese, it's Direct Input by default, indicated with an "A". (I know nothing about this except it uses some direct mapping to the keyboard. Most people don't type this way.)
6. To change this, either:
   1. click on it until it changes to the desired method,
   2. use [Shift+space] on your keyboard until it changes to the desired method,
   3. or right-click the indicator and select a method from the list.
   On the toolbar, hiragana method is indicated by あ("a").
7. Type a Japanese word phoenetically, such as "nihongo"; hiragana will appear with a zig-zag underline, not Roman characters!
8. As soon as enough is typed to spell an acceptable word, a candidate list will appear. This often happens as soon as a short word is recognized. If you are typing a longer word, or even an entire phrase or sentence, you can ignore it and continue typing. The list will continue to update!
9. When you finish your word, press [Enter] if want to keep the hiragana. Otherwise:
   1. press [space] repeatedly until the desired candidate is highlighted, then press [Enter]
   2. or use the down/up arrow on your keyboard, then press [Enter]. (If the list is long, it will scroll as you move down.)
10. You may type as many chunks at a time as you want in this fashion.
11. When you wish to switch languages, click the icon and select English from the menu.
12. Alternatively, you can copy-and-paste directly, as from a dictionary or web page.