JAST Co., Ltd.
a.k.a. Japan System Technology
Established in 1985 and went bankrupt in 2001.
Cocktail Soft was a collaboration with Kirara when they were still related, hence the name of the brand. Even though Cocktail Soft is linked to JAST as an imprint, this link is dead since Kirara changed its name to IDES and kept the brand for itself while breaking ties with JAST.