Girls² (pronounced "Girls Girls") is a Japanese idol girl group formed by LDH in 2019. The group consist of EXPG Studio graduates who starred in Takashi Miike's Girls × Heroine series. The group debuted in June 2019 with the release of their first single, "Daijyoubu."

In December 2015, Yuzuha Oda, previously a member of the idol girl group Amorecarina, participated in the TV Girls Drama Audition held by Ciao, Pucchigumi, and LDH, winning a starring role in the 2017 series Idol × Warrior Miracle Tunes! as Fuka Tachibana, a member of the girl group Miracle². Oda performed and portrayed her character on television and music events with the rest of the Miracle² members. When Idol × Warrior Miracle Tunes! became successful, LDH held the TV Girls Drama Audition in summer 2017 for the next installment of the series, Magical × Heroine Magimajo Pures!, which Momoka Sumitani, Misaki Tsuruya, Youka Ogawa, and Kurea Masuda had won starring roles as Rin Shirayuki, Mitsuki Hanamori, Shiori Hoshina, and Yuria Nijiiro. They released music for the series under the group name Magical², portraying their characters on television.

After the musical success of Miracle² and Magical², LDH debuted all previous members signed to their company as a supergroup named Girls², along with cast members from the newly announced 2019 series Secret × Heroine Phantomirage!, Minami Hishida, Kira Yamaguchi, and Toa Harada, winners in the actress category of the 2018 LDH The Girls Audition and members of the girl group mirage². Prior to entering acting, Sumitani, Ogawa, Masuda, and Yamaguchi were part of EXPG's U-14 female trainee group, Kizzy.

Approximately 2,000 people attended their debut showcase in Osaka. As a group, Girls² released their debut single, "Daijyoubu", on June 26, 2019, as the opening theme song for Secret × Heroine Phantomirage! On July 6, 2019, Ran Ishii, a new cast member Secret × Heroine Phantomirage! and their tie-in group, Mirage², was added as a member. She made her official debut with the group on October 30, 2019, with their first mini-album Koisuru Kamo.

Girls2 have collaborated with popular sports brand FILA and the kids streetwear TEG TEG.

Girls2 placed 3rd on Mercari's rank of 2019's most "trendiest word" and Ran Ishii ranked 20th on the second half of 2019 TV Appearance Ranking.

In December 2019, Girls² announced they will be performing the theme song, "ABCDEF Girl", for the film Gekijōban: Secret × Heroine Phantomirage!: Eiga ni Natte Chōdaishimasu. Their song "Guru Guru" was also used as the theme song for 2020 film Eiga: Neko Neko Nihonshi: Ryūma no Hachamecha Time Trouble ze yo!

On November 17, 2019, Girls2 announced their first Live Tour "Girls2 LIVE TOUR ~Chuwapane~" that would run in 8 towns starting from March 7 until June 28, 2020. They were also the opening act for E-girls PERFECT LIVE 2011 2020. To commemorate the tour, a Girls2 cafe was announced to run from March 20 to April 6. A documentary titled Girls²: The Miracle of 9 aired on TV Tokyo on March 22 and March 29.