I have examined S. Donaudy's (1879-1925) "36 Arie di stile antico" from various perspectives to analyze the music and content, and shed light upon his unique style and musical phraseology. I find it deeply interesting that, although S. Donaudy has become widely known and received in Japan, his work has garnered little interest in Western countries; there is almost no research into historical documentation regarding his life or music. As a musician, I am determined to research S. Donaudy's music from a variety of angles to uncover and study his intentions by using his musical notes. In this paper, I introduce the content of "SPERDUTI NEL BUIO" (1907), the fourth of S. Donaudy's six operatic works, which are already out of print. One peculiarity is that S. Donaudy's younger brother, A. Donaudy (1880-1941), who was in charge of the text, added an enormous volume of stage direction throughout the opera. This is extremely interesting, since it reveals a common trait shared with the composer S. Donaudy, who demanded a large amount of direction in the music. I believe that performers of this opera are required to use this massive volume of information to accurately reproduce the work, while also adding their own musical interpretation.