The official Dragon Ball website’s seventy-third entry in “The Nearly Complete Works of Akira Toriyama” — an on-going series highlighting rare and important pieces of the author’s work over the years — is a series of design drafts for the title screen of the Dragon Ball Z television series, which debuted 29 years ago today in Japan (26 April 1989):
It was Toriyama himself that coined the “Z” name for the updated television series, which he explains in the TV anime guide Son Goku Densetsu:
— Rumor has it that you titled it after an energy supplement with “Z” in the name.
Toriyama: That’s not true~. (laughs) “Z” is the last letter of the alphabet, right? Anyhow, from that time, I really already wanted to end the comic, (laughs) so I gave the title a “Z” with the meaning of “that’s all, folks~”. I don’t remember saying a single thing about there being an energy supplement. Rumors can be so wild. (laughs)
Nakatsuru: Did you have any image of something other than the “Z”?
Toriyama: No, I probably didn’t. I myself thought, “they don’t really have to change the title, do they?” but someone from the anime staff demanded it, saying “we want to freshen it up”, so I was just sort of like, “this should be fine”.
The “Animation’s Gleanings” column in the final supplemental Daizenshuu notes that other names under consideration were Dragon Ball: Gohan’s Great Adventure, New Dragon Ball, Dragon Ball 2, Dragon Ball: The Wunderkind [Wandā Bōi], and Dragon Ball ’90.
As Toriyama’s original editor Kazuhiko Torishima recounts in his 2016 interview with Forbes, the name change was a convenient extra alongside additional changes being made on the production side of things:
“All of this was great timing as we had all these staff changes happening in the animation as well. The new anime producer also was very smart and said that if we had a new title, in that Dragon Ball would finish and we’d start a new show, then that meant the anime would get more money for promotion. So we decided to go with the different title and updated characters, with bigger proportions, and we had a meeting for this new title but we couldn’t come up with anything good. I went and asked Toriyama for his input and he answered immediately by saying “Dragon Ball Z”. I asked “why Z?” and he said “because this is last, nothing comes after this.””