"Nobody Knows" tells the story of four children: Akira, Kyōko, Shigeru and Yuki, who are aged between five and twelve years old. They are half-siblings, with each of them having different fathers. Because three of the children are in the apartment illegally, they cannot go outside or be seen in the apartment, and do not attend school. Their mother leaves them alone for weeks, and finally does not return; they were forced to survive on their own. Over time, they can only rely on each other to face the multiple challenges in front of them.

Nobody Knows was first shown at the 2004 Cannes Film Festival. It won several awards such as the Best Actor at the 2004 Cannes Film Festival and the Grand Prix at Film Fest Gent.