久住小春 (Kusumi Koharu) is a model, actress, TV personality and singer. She is a former member of the idol group Morning Musume. and the side unit Dream Morning Musume., as well as a former exclusive model for the fashion magazine CanCam. Kusumi joined Morning Musume. in 2005 as the only seventh generation member, being only twelve years old when she joined. Shortly after joining, she was given the role of Tsukishima Kirari for the anime Kirarin☆Revolution. She became the youngest Hello! Project soloist to debut following the release of "Koi☆Kana". She graduated from Morning Musume. and Hello! Project on December 6, 2009 to pursue a career in modeling. As a Hello! Project soloist under the name Tsukishima Kirari starring Kusumi Koharu (Morning Musume.), her highest selling single is "Balalaika" with 72,709 copies. Her lowest selling single is "Hapi☆Hapi Sunday!" with 14,468 copies sold.

Es el miembro único de la séptima generación de Morning Musume, cosa que no había pasado desde que Maki Goto se unió como la única miembro de la Tercera Generación. El proceso de audición y primera aparición pública de Koharu fueron televisados en el programa Hello! Morning durante el 2005. Koharu ha sido miembro del equipo de balonmano del Hello! Project "Metro Rabbits H.P." desde su formación a inicios del 2006. Desde el 07 de abril de 2006 ha sido actriz de voz para el personaje Kirari Tsukishima del anime shoujo Kirarin Revolution.