Kim Se-jeong known mononymously as Sejeong, is a South Korean singer, actress and songwriter signed under Jellyfish Entertainment. Aside from singing, Kim established herself as an well-loved mainstay in variety shows with her multiple streak guesting in popular entertainment programs. She landed her first major acting role as the lead in KBS2's teen drama School 2017 of which she bagged the "Best New Actress" awards.
“I Wanna Hear Your Song” is a mystery romantic comedy about a timpanist Hong Yi-young and suspicious tone-deaf pianist Jang Yoon. Yi Young suffers from insomnia after getting traumatized by what happened on ‘the day’ and comes across Yoon who helps her remember. They try to put Yi Young’s forgotten memories together and the truth about the murder case that traumatized Yi Young.