OS☆K

 is an idol group based in Nagoya. They are a sister unit of OS☆U. They debuted on September 23, 2021.

Current Members

 * Matsunaga Aika (松永あいか; ) (Founding member)
 * Orihara Sakura (織原さくら; ) (Founding member)
 * Himekawa Kana (姫川かな; ) (Joined August 6, 2022)
 * Yamada Airi (山田愛莉; ) (Joined August 6, 2022)
 * Mimori Yuuri (美森悠吏) (Joined May 3, 2023)
 * Itagaki Arisa (板垣有砂) (Joined May 3, 2023)
 * Natsuki Nene (夏木寧音) (Joined May 3, 2023)
 * Suzume Hana (鈴明華) (Joined May 3, 2023)
 * Niiyama Renka (新山恋歌) (Joined May 3, 2023)
 * Ichinose Mai (一ノ瀬まい) (Joined May 3, 2023)
 * Iinaka Nako (飯仲菜心) (Joined May 3, 2023)
 * Hoshino Yuna (星乃ユナ) (Joined May 3, 2023)
 * Saran Himari (紗蘭ひまり) (Joined May 3, 2023)

Former Members

 * Takahashi Rui (髙橋流唯) (Founding member; Withdrew pre-debut)
 * Ichinose Soraha (一之瀬天葉) (Founding member; Withdrew October 29, 2021)
 * Tachibana Kyoka (橘杏佳) (Joined pre-debut; Graduated March 18, 2022)
 * Usami Mii (宇佐美みい) (Founding member; Graduated April 4, 2022)
 * Hano Kanon (羽乃花音) (Founding member; Withdrew May 30, 2022)
 * Konatsu Yuana (小夏ゆあな) (Joined pre-debut; Graduated June 4, 2022)
 * Izumo Yae (出雲やえ) (Founding member; Transferred to OS☆U June 4, 2022; Last live with OS☆K June 9, 2022)
 * Ayase Hikaru (絢瀬ヒカル) (Joined March 5, 2022; Transferred to OS☆U June 4, 2022; Last live with OS☆K June 9, 2022)
 * Aoi Minato (蒼井湊; ) (Founding member; Transferred to OS☆U March 20, 2023)
 * Minami Miyuka (南みゆか; ) (Founding member; Transferred to O₂ April 29, 2023)
 * Nishino Kokoro (西野心桜; ) (Founding member; Transferred to O₂ April 29, 2023)
 * Yumeno Misaki (夢乃心咲; ) (Founding member; Transferred to O₂ April 29, 2023)
 * Momose Hiyori (桃瀬ひより; ) (Founding member; Transferred to O₂ April 29, 2023)
 * Nohara Yuina (野原ゆい菜; ) (Joined August 6, 2022; Transferred to O₂ April 29, 2023)
 * Satomai Juna (里苺樹奈) (Joined May 3, 2023; Withdrew June 30, 2023)
 * Nanase Nana (七瀬なな; ) (Founding member; Graduated July 15, 2023)