From Translated Treasures:

Sometime in the near future, Tokyo is being ripped apart by a coup d'etat. The Chinese mafia, the American military, and the Japanese Special Forces are all trying to promote their own interests. Now several street kids have joined the fight in an effort to take back their nation by destroying the newest weapon, mutated radioactive flowers that release LSD. The trouble all began when a space shuttle caught fire during re-entry and crashed into a Chinese nuclear facility. For half a year after that, ash rained down on Tokyo, and now nothing blooms there.

The story alternates between this many-sided war, and Crow's past. Crow is the leader of the street kids. He was raised by a man named Shana, a man famous for his ability to agitate large crowds. Shana has been missing for many years, and was presumed dead.