Tohl Narita: “In a word, it is a sen-nin. As there is nothing interesting if it’s all white (while the set would be white too*), I made its face dark. Even though I initially drew A, it looked too much like a sen-nin, and I drew B instead by flattening its head.”
*Narita’s own remark
Sen-nin means a wizard or hermit seen as immortal living in the mountains while it should have originated from Taoism and the word is often used in Japan to refer to someone living in the mountain, not necessarily in seclusion or for a religious purpose, saying something like “He’s a man just like a sen-nin living so deep in the mountain” apart from the Chinese religion (I believe most Japanese people are even unaware that the idea of sen-nin originally came from Taoism even though the word itself is so familiar to them).
It seems that Yuzo Higuchi who directed this episode featuring Woo had something more like an abominable snowman in mind and that he realized the actual costume had excessively long hair when he looked at it for the first time. But he says, as he didn’t know a kaiju like an abominable snowman (Guigass) had already appeared in the show then, the design of Woo is now fully acceptable to him.
As to its sculpture, the costume was made by Ex Production instead of Ryosaku Takayama following Goldon that appeared in the previous episode.
Keizo Murase who was with Ex Production back then says they used plant fabric of Manila hemp usually called “sutaffu (stuff?) among them. Even though the stuff is usually rather short in length, he says they obtained the long one from a bike store which used to be located right across Toho because the store owner had a lot of knowledge of the fabric material as they also dealt with ropes (I don’t exactly understand why ropes can be associated with a bike store).
Tetsuo Yamamura says the Woo costume was very light in weight with the long hair just covering the lower part of the body like a straw skirt with nothing to cover the actor’s body while the actor looked out through the bunch of hair so that his face could have been exposed if the covering hair should have been pushed aside.