O₂

 (オーツー) is a five-member idol group. They made their stage debut on April 29, 2023 @Nagoya Diamond Hall.

The members are all former members of OS☆K.

Members

 * Minami Miyuka (南みゆか; ) (Founding Member)
 * Nishino Kokoro (西野心桜; ) (Founding Member)
 * Yumeno Misaki (夢乃心咲; ) (Founding Member)
 * Momose Hiyori (桃瀬ひより; ) (Founding Member)
 * Nohara Yuina (野原ゆい菜; ) (Founding Member)