The state one reaches by the age of 9 (2011/2024) is a sound video installation based on an essay by mathematician Oka Kiyoshi dealing with the emotional development of human beings. As the organic and rhythmical animation develops, the germination of human sensibility appears and disappears on screen, along with drawings and notes of thoughts that also reference Aoki and Ito’s own experiences. The work brings us to newly reflect upon the emotional development that humans have repeatedly undergone from the primitive to the modern age, through the shared experience of watching people grow.