Hey @Lucky Jellyfish!
I'm not aware of any API that could provide that service, however, what you can do is fill a paste on Pastebin: create an account so you can edit the paste in the future, and make sure to set the expiration date to never.
The paste should be filled like this:
JAPANESE_KANJI_CHARACTER_1|
JAPANESE_KANJI_CHARACTER_2|
JAPANESE_KANJI_CHARACTER_3|
...
LAST_JAPANESE_KANJI_CHARACTER
Notice how every line ends with a | (vertical bar), except for the last one that doesn't need it, replace JAPANESE_KANJI_CHARACTER with your text, but make sure each character presentation doesn't go above 500 characters, and that you don't use the | (vertical bar) in the text anywhere else than at the end of the presentation.
Then use the following code in the Timer:
$(eval c=`$(urlfetch json https://pastebin.com/raw/XXXXXXXX)`.split(`|`); c[Math.floor(Math.random()*c.length)])
Replace XXXXXXXX in the command by your paste ID.
Note: if you need to use the | (vertical bar) in your characters descriptions, then replace the one at the end of every description with another character you won't use, and replace it inside the ``.split(|)`` as well.