Hit wo Nerae! (2004)

Mitsuki Ikuta works for the Houchiku Corporation, making movies. To all who know her, she is perceived as being a very infantile woman, still wearing childish fashions. A fan of the detective movie genre, she suddenly finds herself chosen to be the main producer of a new film—but it's a "hero movie" (a genre generally considered childish). Determined to succeed, regardless, she takes on the job. (Source: ANN)