ASL Starter Kit Module #4 PTO brings ASLSK to the Pacific Theater of Operations (PTO), and adds the Japanese and the United States Marine Corps to the ASLSK lineup. ASLSK#4 is a self-contained ASL module that gives players the opportunity to start playing Advanced Squad Leader almost immediately.

ASLSK#4 expands on the themes of previous Starter Kits by providing new counters and updated rules featuring a new concept to Starter Kit - PTO. At the heart of this module are the rules for using the Japanese Imperial forces who fought amongst the jungle and island atolls of the Pacific in terrain completely different from the European Theater of Operations and with tactics different than their European counterparts. In addition to the step-reducing Japanese infantry and new rules for familiar looking terrain, simplified rules for Banzai, concealment, and hand-to-hand close combat are introduced. Neither components nor experience with earlier Starter Kits is necessary to play.

The eight scenarios and three mapboards cover actions between the U.S. forces (Marines and Army) that opposed the Imperial Japanese Army on the islands of the Pacific and in the exotic China-Burma-India theater. From Guadalcanal to Myitkiyina to the big island of Luzon in the Philippines, these forces fought to the death from 1942 to 1945.