2011

2011 is the year the 9th and 10th Generations joined Morning Musume; S/mileage added new members; and Takahashi Ai, Maeda Yuuka, and Ogawa Saki graduated Hello! Project.

Members

 * January 2: Fukumura Mizuki, Ikuta Erina, Sayashi Riho, and Suzuki Kanon join Morning Musume as the 9th Generation
 * January 12: MM Gakuen Gasshoubu disbands
 * January 28: Dream Morning Musume is formed
 * January ?: Mori Saki and Furukawa Konatsu graduate from Hello! Pro Egg
 * February 21: Ohno Munehiko and Eric Fukusaki join Up-Front Agency
 * March 3: Up Front Girls is formed
 * March 27: Lilpri disbands
 * March ?:
 * Kitahara Sayaka, Sato Ayano, Sekine Azusa, and Arai Manami graduate Hello! Pro Egg
 * Tanaka Anri leaves Hello! Pro Egg
 * April 5: Gabaro Nippon Ai wa Katsu is formed
 * April 17: SI☆NA disbands
 * April 18: Saho Akari graduates from Hello! Pro Egg
 * May 1: Matsui Yurie and Okada Reiko graduate from Canary Club and NICE GIRL Project!
 * June 19: Yoshihashi Kurumi, Hamaura Ayano, and Taguchi Natsumi join Hello! Pro Egg
 * June 20: Otsuka Aina, Mogi Minami, and Ogawa Rena join Hello! Pro Egg
 * July ?:
 * Up Front Girls becomes Up Up Girls (Kari)
 * Many HAPPY! STYLE members (including YuiKaori, Noto Arisa, and Matsunaga Maho) leave Up-Front Agency and join Style Cube
 * August 14: Nakanishi Kana, Kosuga Fuyuka, Takeuchi Akari, Katsuta Rina, and Tamura Meimi join S/mileage as sub-members
 * September 9: Kosuga Fuyuka leaves S/mileage
 * September 25: Okada Sayana leaves NICE GIRL Project! Kenshuusei
 * September 29: Iikubo Haruna, Ishida Ayumi, Sato Masaki, and Kudo Haruka join Morning Musume as the 10th Generation
 * September 30: Takahashi Ai graduates from Morning Musume and Hello! Project
 * September ?: Nagasawa Wakana and Jang Da Yeon leave Hello! Pro Egg
 * October 7: Reborn Eleven is formed
 * October 16: S/mileage sub-members become full members
 * October 17: Reborn Eleven disbands
 * November 12: Yamaga Kanae and Oda Sakura join Hello! Pro Egg
 * December 2: Oshikiri Sayaka leaves NICE GIRL Project! Kenshuusei
 * December 28: StylipS is formed
 * December 31: Maeda Yuuka graduates from S/mileage and Hello! Project
 * ??: Yamashita Mizuki leaves NICE GIRL Project! Kenshuusei