A girl confined to a mental institution recites the same two words over and over. Every day, her sister visits and asks her the one question that can explain her behavior.
When her autistic sister Kyoko accidentally kills their mother Ayame in an accident, Toshi plants a thought into Kyoko's mind that will allow her to escape incarceration--in exchange for mental institutionalization. Toeing the line between love and filial obligation, they escape from the law but not their consciences.