Kusumi Koharu was born in Niigata on July 15th, 1992. She joined Morning Musume. in April 2005 during the second round of auditions. The original Lucky7 auditions, which were held in order to find members for Morning Musume.'s seventh generation, ended without a winner. Manager Tsunku started a second round of casting, Morning Musume. Audition 2005, in order to find the super group's new hope, the new "ace" member. At the time, the fans thought that an older and more mature candidate would be chosen but Tsunku was set on choosing young Koharu, who was only 12 at the time. She was given the nickname, Mirakuru member (miracle member), and no other Morning Musume. member has even been given the privilege of such a promising nickname, which would also lead to a promising career.
In July 2005, Koharu and the rest of Morning Musume. entered the charts with the single Iroppoi Jirettai. The single was a success and much of that was due to the "new blood" in the group. Koharu seemed to be at ease and was well prepared to perform her idol duties. She was immediately adopted by her comrades who felt that it was their duty to protect her and Michishige Sayumi was chosen by Tsunku to become her mentor. Koharu participated in her first concert, Hello! Project's 2005 Summer Tour, and also participated in the autumn tour. The tour's title, for the first time in the group's history, included a new member's name and was entitled Concert Tour 2005 Natsu Aki "Baribari Kyoushitsu ~Koharu-chan Irrashai !~.
In April 2006, Koharu was chosen as the seiyuu for the heroine in the show "Kirarin ☆ Revolution", a new anime about idols and their world. Her solo debut single, Koi Hana, was released in July and she was invited to take part in a few musical shows. Meanwhile, Koharu's single sold very well and stayed in the Oricon charts all summer, selling more than all solo members' works for the summer combined. After this success, she released a second single in October and also a mini-album from "Kirarin ☆ Revolution", in which Koharu's fans heard new material.
By the following year, Koharu was chosen to join the Morning Musume Tanjō 10nen Kinentai unit to celebrate Morning Musume.'s ten year anniversary. The unit was shortlived, but released two singles and three DVDs. Over the next two years, she participated in a number of Hello Project related groups, including ZYX-α and Kira Pika, while still producing her own music. Between summer 2008 and spring 2009, she released two singles and two full albums. However, despite her popularity, Hello Project announced in September that Koharu would be graduating from Morning Musume., and she performed for the final time on December 6th, during the Nine Smile tour.
Although she has graduated from the music scene, Koharu is still thriving in the Japanese entertainment world. Along with her regular appearances on children's TV shows "Oha Suta" and "Oha Coro", she also dabbles in modeling and advertisement.
