Undead (Yoasobi song)

"Undead" is a song by Japanese duo Yoasobi, serving as the theme for anime series Monogatari Series: Off & Monster Season (2024). It was released as a single on July 1, 2024, by Sony Music Entertainment Japan. Written by Ayase, the song was based on the light novel Monogatari writer Nisio Isin's short stories Nadeko Past and Shinobu Future.

Background and release
In January 2024, an anime adaption of two sagas of light novel series Monogatari—"Off" and "Monster" seasons—was announced, set to premiere in the same year. Later, on May 1, the official website of the anime series teased the upcoming announcement by countdown with an image of the letter "Y" on a red-pink background, as well as posted the image by the official X (formerly Twitter) account for the writer Nisio Isin's anime project. The next day, the anime series confirmed that Yoasobi would perform the theme song for Monogatari Series: Off & Monster Season, titled "Undead".

In the press release, Ayase stated: "The Monogatari series has such a strong attachment to me that when asked about my favorite anime, I always answers Bakemonogatari." He also revealed in a Comic Natalie interview that he wrote the song about the Monogatari character Hitagi Senjōgahara when he was 18–19 and often performed it live with his rock band. A snippet of the song was previewed via the trailer of the anime's first two arcs Orokamonogatari and Nademonogatari on May 3. Around two months later, on June 24, the duo additionally teased the song via their social media. Five days later, they revealed the song's release date, to be July 1, 2024, and its cover artwork, featuring the character Yotsugi Ononoki making a V sign with both hands.

Lyrics and composition
"Undead" was sourced from two short stories written by Nisio, Nadeko Past (なでこパスト) and Shinobu Future (しのぶフューチャー), published on the anime's website the same day as the song release. Both stories told the Monogatari characters Nadeko Sengoku and Shinobu Oshino lying on a sofa and receiving counseling from Yotsugi Ononoki about their nervousness. Ayase compared the short stories to his mental gloom at the time he wrote about his musical novelty losing. Musically, he composed the "danceable and very bright" music based on the image of Monogatari as a whole, rather than the short stories. Tomoyuki Mori from Real Sound described the song as a "perfect blend of kick and bass that reaches deep into the body," the track that "intertwines brilliant and sharp synth phrases," and the inorganic melody that reminisces about early Vocaloid music.

Commercial performance
"Undead" debuted at number two on the Oricon Digital Singles Chart for the issue dated July 15, 2024, with 18,199 digital sales, behind Be:First and Ateez's "Hush-Hush". For Billboard Japan charts, the song entered the Japan Hot 100 dated July 10 at number ten. It also landed at number two on the component Download Songs and number 17 on the Streaming Songs, earning 17,284 downloads and 4,791,166 streams in its first week. Additionally, "Undead" debuted at number four on the specific-genre Hot Animation chart.

Credits and personnel

 * Ayase – writer, producer
 * Ikura – vocals
 * Satoru Taguchi – guitar
 * Nisio Isin – based story writer