Z4-B1

 is a group within Zero Project. The theme of the group is royalty.

The first line-up was announced on November 20, 2021.

They made their stage debut on November 21, 2021 @Ebisu Garden Hall.

Current Members

 * Ato Rie (あとりえ) (Joined March 6, 2023)
 * Amamiya Mizuki (雨宮美月) (Joined March 6, 2023)
 * Inoue Sakura (井上咲愛) (Joined March 6, 2023)
 * Tsukishima Mimika (月島美々花) (Joined March 6, 2023)

Former Members

 * Shukuzu Nuko (酒屑ぬこ) (Founding member, Graduated February 28, 2022)
 * Tsukino Mizuki (月野みずき) (Founding member)
 * Asahina Rin (朝比奈凛) (Founding member)
 * Ueda Moca (上田望夏) (Founding member)
 * Yuzuki Misato (雪月みさと) (Founding member)
 * Misora Rin (海空凜; ) (Joined November 29, 2022)
 * Miyata Yume (宮田有萌) (Joined November 29, 2022)
 * Tadano Honyon (只野ほにょん) (Joined November 29, 2022)
 * Tsushiro Mai (蕾白苺; ) (Joined November 29, 2022)
 * Rinka (凛華; ) (Joined November 29, 2022)
 * Ayase Mayo (絢瀬まよ; ) (Joined December 28, 2022)
 * Isshiki Hiyori (一色陽頼; ) (Joined December 28, 2022)
 * Hanamaru Yuzu (花円柚羽; ) (Joined December 28, 2022)
 * Yoi (宵; ) (Joined December 28, 2022)
 * Ogawa Urara (小河うらら) (Joined March 6, 2023)