Etsuko Yakushimaru Metropolitan Orchestra is a musical project alias of the Japanese artist, singer, composer, and producer Etsuko Yakushimaru. The name is one of several alternate identities used by Yakushimaru, who is also known for being the lead vocalist of the band Sōtaisei Riron and for other solo projects such as Yakushimaru Experiment and the duo Etsuko Yakushimaru & d.v.d. As a creator, Yakushimaru is active across a wide range of fields including pop music, experimental music, art, and literature, and is known for her independent and often avant-garde approach.

The Metropolitan Orchestra project is most recognized for its connection to the anime series Mawaru Penguindrum. In 2011, Etsuko Yakushimaru Metro Orchestra released the double A-side single Nornir / Shōnen yo Ware ni Kaere. The single was released on the King Records label and both tracks were used in connection with the anime. The song Shōnen yo Ware ni Kaere, which translates to Boy, Return to Me, and the song Nornir both serve as theme music for Penguindrum.

The single features a rich ensemble of musicians. For the track Nornir, the arrangement was handled by Naoko Eto, who also played piano, with Makoto Otsu on guitar and Taisei Aoki on trombone. For Shōnen yo Ware ni Kaere, the arrangement was done by Kenji Kondo, who contributed guitar and piano, with Kumiko Takara on percussion, Masakuni Takeno on tenor saxophone, Eijiro Nakagawa on trombone, and Eric Miyashiro on trumpet. Etsuko Yakushimaru provided all vocals and chorus work, and also produced the single. The lyrics and music for both songs are credited to her under her songwriting alias, Tica・α.

The musical identity of Etsuko Yakushimaru Metropolitan Orchestra reflects her broader artistic style, which blends art-pop grandeur with theatrical vocals and a fusion of organic and electronic instruments. The sound is characterized by whimsical and surreal melodies, often incorporating retro-futuristic cabaret elements and detailed, story-like lyrical narratives. The project showcases her ability to work on a grand scale, incorporating orchestral and brass arrangements into her unique pop framework.

The industry significance of this alias lies in its representation of Etsuko Yakushimaru’s versatile and independent creative control. By releasing music as the Metropolitan Orchestra, she signaled a departure from her work with Sōtaisei Riron, creating a specific sonic identity for her anime collaborations. The success of the Penguindrum theme songs cemented her reputation as a sought-after artist for anime soundtrack work, leading to subsequent theme songs for other major series such as Space Dandy and Sailor Moon Crystal under her various solo names. The single remains a key entry in her discography and a prime example of her ability to merge experimental pop sensibilities with mainstream anime media.