Haven't found much info. on the electric typewriter made by Citizen (the S4-U model)...but did find Robert Messenger's article about the Citizen X3 manual typewriter.

Some useful info. about Citizen's foray into typewriters and the designer behind both the X3 and the S4-U.

https://oztypewriter.blogspot.com/2012/01/curious-case-of-citizen-typewriter.html

Here is a photo of the X3 manual typewriter.

And I even found some photos of a more simple F2 manual typewriter, also made by Citizen (which Robert Messenger may not have been aware of at the time of writing his article).
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Of my 13 typewriters, only one (my Citizen S4) is electric. My better half spotted it in a thrift store and bought it for me for $10. It’s a workhorse. I keep it plugged in and ready to use while the manuals rotate their turns at the typing station.