Hidden Gems

The Hidden Gems were the three members, Moe Suzuhana, Urara Takatsuji and Aina Takeda of 22/7 who did not debut with the other eight members. In Japanese the term is 隠し球 (かくしだま, Kakushidama) meaning "Hidden Balls" or "Concealed Balls."

Characters

 * Mikami Kamiki
 * Yuki Tojo (Graduated on December 26, 2021)
 * Tsubomi Hiiragi (Graduated on December 26, 2021)

Seiyuu

 * Moe Suzuhana
 * Urara Takatsuji (Dissmissed on November 1, 2021)
 * Aina Takeda (Graduated December 31, 2021)

History
Although the initial goal was to debut with all 11 members, many of the early events were carried out without them. The 7/22/17 live event was rehearsed without them. However all eleven members were taking the same lessons together.

The three members' faces were not revealed until the 7/22/17 live event.

11 Nin ga Atsumatta Riyuu was the first song that included them with the rest of the members.

The three characters voiced by Moe, Urara and Aina were revealed on September 20, 2018 as Mikami Kamiki, Yuki Tojo and Tsubomi Hiiragi respectively.

Nani mo Shiteagerarenai marked their first title track performing with the other eight members.

While the three members didn't appear in the main series of the anime, they appeared in the bonus thirteenth episode titled "8+3=?" Respectively they sung the ending song for the episode, Kamisama ni Yubi wo Sasa Reta Bokutachi.

On September 30, 2021, it was announced that Aina would graduate from 22/7 at the end of December.

On November 1, 2021, it was announced that Urara was dismissed from 22/7 due to breach of contract relating to absence from work without permission and being unable to be contacted.

On December 26, 2021, it was revealed that the characters Yuki and Tsubomi had graduated from the group.

On December 31, 2021, Aina graduated from the group.