how to display extra little characters above characters in a Text?

I'm revisiting an old need: displaying furigana (little phonetic characters that show how to pronounce Chinese characters in Japanese text). The result should look like this:


Those small characters above the main line of text are what I'm talking about.

I have good code for doing this in the old OnGUI system, but for the new UI system, it's...

how to display extra little characters above characters in a Text?