Actress Takako Matsu (32) is starring in "Kokuhaku," a new film by director Tetsuya Nakashima ("Kamikaze Girls"). The film is an adaptation of Kanae Minato's mystery novel of the same name, which became one of the best selling books this year.

The story takes place at a junior high school. During a homeroom session after the end-of-year closing ceremony, the teacher Moriguchi (played by Matsu) informs her students that she has decided to quit, but adds in a surprising confession - her four-year-old daughter who drowned in the school's pool was actually killed by two of the male students in the room. She begins to take revenge by declaring that she has infected them with the HIV virus, and the truth behind the incident starts to unravel.

The class of 37 students were chosen from an audition of more than 1,000 applicants. Masaki Okada (20) plays Moriguchi's enthusiastic replacement, while Yoshino Kimura (33) plays the mother of one of the targeted boys that has become a hikikomori.

Filming started on October 24. Theatrical release is scheduled for summer 2010.