She is a former tenth-generation member and sub-leader of the pop group Morning Musume and former model for the Japanese fashion magazine Love Berry.

[3] On September 29, 2011, at a concert at Nippon Budokan, which was part of Morning Musume Concert Tour 2011 Aki Ai Believe: Takahashi Ai Sotsugyō Kinen Special, it was announced that Haruna Iikubo passed the auditions alongside three other girls: Ayumi Ishida, Masaki Satō and Haruka Kudō, and would be joining Morning Musume.

[4] On April 18, 2012, it was announced that Morning Musume's Tanaka Reina and the 9th & 10th Generation members would participate in a new stage play titled Stacey's Shoujo Saisatsu Kageki.

On July 20, it was announced that Iikubo, Yajima Maimi, Tokunaga Chinami, Natsuyaki Miyabi and Nakajima Saki were chosen to form the unit DIY♡.

[6] On December 15, Iikubo announced she would produce and lend her voice to the virtual idol Ni-na under the VR corporation HIKKY.