Lee Seo-yeon, known professionally as Y:SY, is a South Korean singer-songwriter and rapper under H1GHR Music. She is a former member of the girl group fromis_9, formed through the reality survival show Idol School (2017). She left the group in 2024. She made her solo debut on November 17, 2025, with the digital single Naked.
2025Duckbap HouseTV showas Self · 1 episodes2023Jae Joong and FriendsTV show1 episodes2023fromis_9 concert ＜LOVE FROM.＞ IN JAPANMovie2022fromis_9's Autumn NightTV showas Self · 13 episodes2022fromis_9's Summer NightTV showas Self · 9 episodes2022Lee Mujin ServiceTV showas Guest · 1 episodes2021The Game CaterersTV showas Self · 3 episodes2020The Silence Of IDOLTV showas Self · 2 episodes2019We See WinterTV show2 episodes2018Welcome to Heal InnTV show4 episodes2017Fromis's RoomTV show5 episodes2017프롤로그_프로미스의 방 엿보기TV show1 episodes2017Idol SchoolTV showas Self - Contestant · 11 episodes