iam not sure can this design work or not but i want to share, it actually base from Dragonball Chair design for the saiyan but iam not sure is it made by the original creator or not though, but i cant found the image, so i use rough photoshop to this chair instead to help visualize it.

 so in the design it have a slit in the middle back and some have combination of a reverse toilet hole too, to accomodate different tail angle.

original image from:https://www.diotti.com/en/hole-single-piece-polypropylene-chair.html
[![enter image description here][1]][1]

for visual image of the reverse toilet hole dont take it literal (some even reach to the middle part and big like toilet hole i dont use toilet one because someone may get disgusted or considered not aproriate) but combine it with the slit design basically extend the slit to there.

from: https://www.amazon.com/slp/chair-support-for-lower-back-pain/9uunpf37wnxx3r3
[![enter image description here][2]][2]
 


  [1]: https://i.sstatic.net/EEV75.jpg
  [2]: https://i.sstatic.net/Tel7b.jpg