Kim Seon-you (김선유), known as SEONYOU, is CLASSy’s youngest member, main rapper and lead dancer. She joined the group after competing on MBC’s My Teenage Girl and debuted on May 5, 2022.

SEONYOU brings a rhythmic style to CLASSy’s performances, delivering rap passages that contrast with the main vocalists’ melodic lines. Her dance work also adds energy to the group’s synchronized stage formations. Together, these roles give her a distinct identity within the seven-member line-up.

Her individual song Pigeon appears on CLASSy’s June 2026 release RE:BOOT [AFTER TEARS]. The official solo performance clip lets listeners focus on her delivery outside the usual group arrangement. Although the song is performed individually, it remains part of a CLASSy album rather than a separate solo debut.