Takayama is likely to have written in his diary that Narita spent two or three hours in Takayama’s Atelier May while correcting the design of Dada looking at books of ancient art and African art borrowed from Takayama although Narita had come to the atelier with the Dada design three days before to stand by for having the Gomora costume tried on by someone.
Narita and Takayama seem to have initially tried to design the head to rotate so that the three different faces show up sequentially with the other two covered with lids in the double-door style while one of the three would face forward, whereas it didn’t do the trick. So it was redesigned to enable the head to show the different faces in another way.
Tetsuo Yamamura says in a book that it was decided they would simply replace the faces by attaching one of them onto the core part that looked like a head with black hair (such a hairstyle is called okappa in Japan, probably from the imaginary creature kappa. So Dada is often associated with the hairdo jokingly like “Dada with an okappa hairdo.” The Japanese artist Yayoi Kusama characteristically has that hairstyle).
Yamamura also says that is why a slight gap can be found between the face and black core head and that, if closely watched, you can find wires between them to tie them together.
As you know, the idea of showing three different faces based on the same head was inherited to “Another Dimensional Man Gigi” in the show “Ultraman Cosmos” that had the varying faces depicted with the use of computer-generated images.