Trivia: The ladies playing the twin fairies (or whatever they were) really are twin sisters, Yumi and Emi Ito. And although they look very young, they were 20 years old when they starred in "Mothra", and 23 when "Godzilla vs the Thing" was made.
Japanese women always seem to look younger than their years, to me.
The original twins from "Mothra" (1961) were an actual singing duo...they worked under the name "The Peanuts" in Japan.
It's kind of funny...in a recent G-film, GMK, Mothra shows up, but the singing twins do not, as it was a far more serious and violent movie. However, at one point, Mothra flies low over a street, and two teenaged twin girls are shown looking up at her and smiling to each other knowingly.