Ron said:
By Ben, the animators of this short are: Koichi Hashimoto, Hideki Kakita, Katsuhiro Shimizu, Hideki Futamura, Mariko Aoki, Masaharu Tomoda, Misao Abe, Toshiko Baba, Masashi Oumi, Shinji Hashimoto + Maybe Satoru Utsunomiya uncredited.

Hideki Futamura and Koichi Hashimoto are regular collaborators and in general, people with similar style to Tatsuyuki Tanaka & Satoru Utsunomiya, if this cut is not them, maybe is just the two going uncredited.

grognarg said:
I read the Anipages article, but it doesn't say anything conclusive. I cursorily checked the web anime style interviews, but didn't see anything there either. So I put "presumed" for now.

Edit: Utsunomiya's involvement seems widely accepted (e.g. Custom Text URL Link1, Custom Text URL Link2), but I didn't find anything about the others.