S01E01 Lost
Akira, the series protagonist, is a participant in a fighting tournament called "Bl@ster," after a successful battle, he retires to his quarters. He's awakened from sleep when a group of police break into his room...
After surviving his first day in Toshima, Akira is surprised when Keisuke turns up; he has followed him into the city. Not letting this change his mission they both set out into the city and are met by Rin who takes them to the Castle, the intake place for Igra.
After being devastated in the third World War (known as The Third Division), Japan was divided in two. Several years after the end of the war, a crime organization called Vischio has taken control of the destroyed city of Toshima (formerly Tokyo, Japan's capital city), where they are holding a battle game known as Igura.