Conversation so far:
What happened to Ai Kago in 2011?
In 2011, Kazuyuki Ito, president of Mainstream, declared that the agency planned on suing Ai Kago for 100 million yen in damages for contract violations.
Are there any other interesting aspects about Ai Kago in 2011 besides being sued for damages?
Ai Kago was rushed to a nearby hospital after agency officials found her on the floor of her apartment with cuts to her wrists.
Was Ai Kago married?
Ai Kago and Haruhiko Ando registered their marriage.
When did Ai Kago and Haruhiko Ando register to marriage?
What happened to Ai Kago after registering marriage to Haruhiko Ando?
Planning to revive her music career, Ai Kago formed an idol group, which was later named Girls Beat!!
Did Ai Kago revive her music career with Girls Beat!!?
Girls Beat!! released their first single, Sekai Seifuku on July 22, 2014.
Did Ai Kago's Girls Beat!!  win any awards?

Question: what was their biggest hit?
Self-contained rewrite: What was Ai Kago's Girls Beat!! biggest hit?