Keiko moves to a new flat with her 12-year-old son Akira. She actually smuggles in three more younger children in and tells them to remain unheard and unseen by their neighbours. The children are hers but of different fathers. She hasn't registered her children and does not send them to school. A few days after Keiko confesses to Akira that she's in love again, she disappears, leaving an envelope with money. The children have to fend for themselves, with Akira in the family head role. They have a very limited occasional interaction with the outside world. An exception is Saki, a withdrawn victim of school bullies, who becomes friends with Akira and his siblings. The youngest, Yuki, dies. But nobody knows of her passing or even that she ever existed.