^Then they were wrong, because it was a Japanese singer who was singing in English, not an American singer replacing the original soundtrack. Lots of movies have singing doubles for their lead actresses -- for instance, Marni Nixon dubbed Natalie Wood's singing in West Side Story
and Audrey Hepburn's in My Fair Lady
. Presumably the makers of Bijo to Ekitainingen
cast Ms. Shirakawa for her looks and non-singing talents and then brought in a popular Japanese jazz singer to record her songs, which were in English since jazz is an American music form. And then, when the film was dubbed into English, the original songs' audio was kept intact -- but some reviewers failed to notice that the lip movements matched (except for occasional synchronization problems) and mistakenly assumed that what they were hearing was added in America to replace a Japanese song.