I got this movie from the mill creek entertainment Sci-fi Creature Classics and Mothra was one of them. Made in 1961 by toho it’s about this island that gets attacked by a atomic bomb. A team of Japanese explorers check out the radiated island and are surprised to see life there. Also there are these twin girls called the Ailenas, or the Peanut Sisters as some people call them.
Some guy takes them to exploit them and they’re singing voices. A bit later when the Peanut sisters sing it awaking’s Mothra which appears about halfway though the movie.
I mostly watched this for the Mothera song which sounds pretty peaceful and beautiful. Also when Mothra finally cocoons into a butterfly or moth it really gets good. If your a monster movie fan check this one out since it’s considered a classic Sci-Fi monster movie.