Monster (EP)

Monster is the debut extended play by Red Velvet – Irene & Seulgi, the first sub-unit of South Korean girl group Red Velvet. It was released on July 6, 2020, by SM Entertainment, with Dreamus serving as the South Korea distributor. The EP contains six tracks, including the title track of the same name and a follow-up single "Naughty".

Background and release
On April 21, 2020, SM Entertainment confirmed that Irene and Seulgi would form Red Velvet's first sub-unit and that the duo was in preparation for their first major release in around June 2020. The release of the mini album was postponed from June 15 to July 6, 2020, on the grounds that it needed additional production on the album, in order to achieve a higher quality of music. The physical release contains two different versions with a CD, a photo booklet, a lyric book and collectibles.

Commercial performance
According to Hanteo, Monster sold over 80,000 copies on its first day of availability, beating Red Velvet's first day and first week album sales records of the group's sixth extended play The ReVe Festival: Day 1, which set the record at 45,080 copies for its first day, and 71,431 copies for its first week. It also became the best-selling girl group sub-unit album of all time, surpassing Twinkle (2012) by Girls' Generation-TTS. The EP reached 100,000 copies sold on Hanteo in under 3 days, making it the first Red Velvet album to do so.

The EP debuted at number five on the Billboard World Album Chart, becoming the duo's top-five entry.

Track listing
Notes:
 * "Naughty" is only available in the EP as a CD-only track. It was omitted from the digital release of the EP until July 20, 2020, when it was released on Korean music sites as part of the EP and as a standalone digital single in international music sites.

Credits and personnel
Credits adapted from the liner notes of the EP.

Musicians


 * Red Velvet – Irene & Seulgi
 * Irene –vocals (tracks 1–5), background vocals (tracks 1–5)
 * Seulgi –vocals (all tracks), background vocals (all tracks)
 * Kenzie –Korean lyrics (track 1)
 * JQ (makeumine works) –Korean lyrics (track 2)
 * Lee Yeon-ji (makeumine works) –Korean lyrics (track 2)
 * Kim Yeon-seo –Korean lyrics (tracks 3, 6), composition (tracks 3, 5–6), background vocals (tracks 3, 5–6)
 * Lee Seu-ran –Korean lyrics (track 4)
 * Park Green (153/Joombas) –Korean lyrics (track 5)
 * Yaakov "Yash" Gruzman –composition (track 1), arrangement (track 1), drums (track 1), keyboards & synths (track 1)
 * Delaney Jane –composition (track 1), background vocals (track 1)
 * Jenson Vaughn –composition (track 1)
 * Yoo Young-jin –composition (tracks 1–2), arrangement (tracks 1–2)
 * Moonshine –composition (tracks 2, 4), arrangement (tracks 2, 4)
 * Louise Frick Sveen –composition (track 2), background vocals (track 2)
 * Charite Viken –composition (track 2), background vocals (track 2)
 * Daniel "Obi" Klein –composition (track 3), arrangement (track 3)
 * Andreas Öberg –composition (track 3), guitar (track 3)
 * Tania Doko –composition (track 4)
 * Maribelle –composition (track 4)
 * MinGtion –composition (track 5), arrangement (track 5), piano (track 5), bass (track 5)
 * Andrew Choi –composition (track 5)
 * Joseph Hong –composition (track 6), arrangement (track 6)
 * Jae Shim –composition (track 6)
 * Kriz –background vocals (track 1)
 * Seo Mi-rae –background vocals (track 2)

Technical


 * Yoo Young-jin –directing (track 1), recording (track 1), digital editing (track 1), mixing engineer (track 1), mixing (track 1)
 * Kenzie –directing (track 1)
 * ButterFly –vocal directing (track 2), Pro Tools operation (track 2), digital editing (track 2)
 * Kim Yeon-seo –directing (tracks 3, 5–6)
 * Kriz –vocal directing (track 4)
 * Jeong Eui-seok –recording (track 1), mixing (track 5)
 * Noh Min-ji –recording (tracks 2, 4–5), mixing engineer (tracks 2–3)
 * Kim Cheol-soon –recording (track 3), mixing (track 2)
 * Lee Ji-hong –recording (track 6), digital editing (track 6), mixing engineer (tracks 5–6), mixing (track 6)
 * Jung Yoo-ra –digital editing (tracks 1, 3)
 * Lee Min-kyu –digital editing (track 4), mixing engineer (track 4), mixing (track 4)
 * MinGtion –digital editing (tracks 5–6)
 * Namkoong Jin –mixing (track 3)
 * Cheon Hoon –mastering (tracks 1–2, 6)
 * Kwon Nam-woo –mastering (tracks 3–5)