Use the candidate window with a Japanese input source on Mac
After you set up a Japanese input source, the candidate window displays all of the candidates available for any kana text you enter (based on words in available Japanese dictionaries). You choose the character or characters to use in your document from the candidate window. If you set the option for predictive candidates, the candidate window shows the most likely candidates to complete your text as you type it, based on what you previously typed and selected.
Note: Typing suggestions that appear in the candidate window also appear in the Touch Bar (if your Mac has one).
Enter characters from the candidate window
On your Mac, switch to a Japanese input source.
In an app, enter Japanese text, press the Space bar until the candidate window appears, then do any of the following:
Press the number that corresponds to the candidate you want to use to select it, then press the Return key to confirm it.
Double-click the candidate you want to use to select it, then press the Return key to confirm it.
Use the Down and Up Arrow keys, or the Space bar and Shift-Space bar to move to the next or previous candidate.
Press the Right Arrow key or Left Arrow key to select the next or previous portion of a text string.
Press Shift-Right Arrow or Shift-Left Arrow to expand a portion of a text string.
After you choose the character or characters from the candidate window, entering the kana again will display the candidate you chose as the first option.
Navigate in the candidate window
On your Mac, switch to a Japanese input source.
In an app, enter Japanese text to display the candidate window, then do any of the following:
Change how candidates are organized: Click the tabs at the bottom of the candidate window or press the Tab key.
Scan through candidates: Use the scroll bar.
Scroll up through candidates a page at a time: Press and hold the Shift key and press the Up Arrow key, press Control-R, or press the Page Up key.
Scroll down through candidates a page at a time: Press and hold the Shift key and press the Down Arrow key, press Control-V, or press the Page Down key.
Get more information about a candidate: Select a candidate with a Book icon
next to it in the candidate window. The additional information appears next to the candidate window.
Change the font used in the candidate window
Some symbols can be displayed using only certain fonts, so you may need to change the font to make sure symbols are displayed correctly.
Characters in documents are displayed using the font set by the app. If the app uses a different font than the candidate window, you might see a different symbol in your document than the one shown in the candidate window.
On your Mac, switch to a Japanese input source.
Click the Input menu in the menu bar, then choose Open Japanese - Kana Settings or Open Japanese - Romaji Settings.
Click Japanese - Kana or Japanese - Romaji in the sidebar, then choose a font and font size for the candidate window.
If a rectangle is displayed instead of the symbol you want, the symbol may not be available in the font you selected.
Tip: To change the highlight color of the candidate window, choose Apple menu 
in the sidebar. (You may need to scroll down.) Click the “Highlight color” pop-up menu on the right and choose a color.