I.O.P. is a faction in Girls Frontline. I.O.P.'s full name is the Important Operation Prototype Manufacturing Company. Almost all in-game collectable/playable dolls are produced by IOP,
or at least a department of IOP.
Sometime around AD 2041, I.O.P. formed as a conglomerate of two large civilian owned companies. I.O.P. were considered pioneers in the development of "dolls", by AD 2046 they have completed the development of the first generation dolls and by AD 2051 they have started productions of second generation dolls.
With Sangvis Ferri being established in 2031, SF's rugged designs soon caught the eyes of IOP, who soon enetered a joint partnership, with IOP providing new designs and research and SF handling the intricate manufacturing work. The partnership did well until the outbreak of World War Three, where IOP found themselves being undercut by SF's more simple and easy to maintain dolls. IOP found themselves pitted against Sangvis Ferri feircly until IOP hired two particularly esteemed researchers, Persica and Lyco. IOP's lead on the Sangvis Company only grew larger as the more personal civilian-model dolls of IOP continued in popularity. Lyco would soon split from IOP, as he became disillusioned with IOP's priorities.