Special to The Japan Times It has been more than four years since key members of the Aum Shinrikyo religious sect carried out sarin gas attacks on the Tokyo subway system. With its principal facilities closed and its guru and his cohorts arrested, the cult has received a crushing blow. Reports say, however, that its subsidiaries racked up more than 7 billion yen in computer sales in fiscal 1998 and that the cult itself still has 2,100 followers and 40 strongholds.