''"[[After School (Songsong)|After School]]"'' ditulis oleh Seo Ji-eum dan Seo Jeong-ah, dikomposisi oleh Daniel Durn, David Quinones, [[Denzil Remedios]], Katrine Neya Klith Joergensen, Jazelle Paris, dan [[Ryan S. Jhun]], juga diaransemen oleh Denzil Remedios and Ryan S. Jhun.<ref>{{Cite web|last=Ahn|first=Jin-yong|url=http://www.munhwa.com/news/view.html?no=20210310MW135831267105|title=컴백 위클리, 타이틀곡은 'After School'…라이언전·서지음·제아 지원사격|trans-title=Weeekly comeback, title track is 'After School'...Ryan Jhun, Seo Ji-eum, JeA support shots.|date=March 10, 2021|website=Munhwa|access-date=May 6, 2021|language=ko}}</ref> Secara musikal, lagu tersebut digambarkan secara "[[Pop music|pop]] dicampurkan dengab [[reggae]] dan [[Trap music|trap beats]]" dan sebuah lagu "menakjubkan" dengan "dinamis [[synthesizer]] dan popping melody". Secara lirij, itu menggambarkan waktu yang "berharga" bersama Teman setelah sekolah.<ref>{{cite web|last=Ji|first=Min-kyoung|url=http://osen.mt.co.kr/article/G1111540357|title=위클리, 오늘(17일) 신곡 'After School'로 컴백..'롱보드' 퍼포먼스 예고|trans-title=Weeekly, today (17th) made a comeback with a new song, "After School". Longboard performance preview.|date=March 17, 2021|website=OSEN|access-date=March 17, 2022|language=ko}}</ref> ''"[[After School (Songsong)|After School]]"'' dikomposisikan dalam kunci [[C-sharp major]], dengan sebuah tempo 164 beat per menit.<ref>{{Cite web|title=Key & BPM for After School by Weeekly|url=https://tunebat.com/Info/After-School-Weeekly/52CBUrIdyf8tbZaUY9iawE|website=Tunebat|access-date=January 26, 2022|archive-date=June 27, 2021|archive-url=https://web.archive.org/web/20210627220411/https://tunebat.com/Info/After-School-Weeekly/52CBUrIdyf8tbZaUY9iawE|url-status=live}}</ref>
