Back in October 2008, Watarirouka Hashiritai was first formed with Watanabe Mayu, Nakagawa Haruka, Ota Aika, and Hirajima Natsumi with school life as its concept.
After some additions and withdrawals of the members, the unit's activities eventually became under the name of Watarirouka Hashiritai 7.
They released 10 singles and 1 album in total, and all of those were ranked in top 10 of Oricon charts.
With the big breakthrough of AKB48, Warota members also began their individual activities.
Last year, Watanabe and Iwasa Misaki (joined in 2010) made solo debuts, and Nakagawa and Ota transferred to JKT48 and HKT48 respectively.
A source associated with the girls explained the reason of their disbandment, "At the time of the formation, its concept was the school life, but now that all the members graduated high school, and each member developed their own individuality, the role of the unit has finished."
It is unknown if they will hold any disbandment performances, but their best-of album is set for release on December 25. Reportedly, the best-of album will consist of 3 CDs which contain 46 songs in total, and 2 DVDs which contain music videos and live footage.