This is a Japanese wargame series published by Sho-Kikaku. "SS" was the initials of "Small size Simulation game".
This series was planned for beginners with low price, simple rules and compact size components (510x360 mm map and 128 counters). Its concept was similar to GDW's Series 120.
But, many games did not adopt common, ordinary, conservative rules, adopted peculiar, strange, experimental rules.
Therefore this series was appreciated by veteran wargamers for short play time.
Many games have been reprinted by Command Magazine Japan and Game Journal.