The story takes place in the far future, when the civilization has declined. Hiyoko is a high school girl, who aims to enter an art university. She runs away from her home because her father tried to throw away her mother's keepsake drawings. She finds a slum located in a stadium and meets the leader of the street children, Akira.

The police attempts to demolish the stadium for the beautification of the city. In order to resist the demolition, the people in the stadium plans to hold a street-art event "The Asylum Session". Hiroko takes the charge of a giant painting on the stadium.