Tokio 

When he was young, Tokio and his brother met a group of thug harassing people in Shibuya, they tried to stop the harassment but his brother end up dead. There is no witness because the two who got harassed went missing, and the gang member were still kids, so they got off free. Follow the incident, Tokio's mom fell ill and later died. 5 years has passed and now Tokio grows up and he returns to Shibuya again to find the one who responsible for his brother's dead.