Grisaia: Phantom Trigger, the adventure game by publisher Frontwing, got a manga adaptation on 15 August 2017 through Akitashoten’s website Champion Cross. It has also been announced that an anime will also be made based on this story, for which Akio Watanabe (Monogatari series and The World God Only Knows) will be the character designer and general director.
The manga will be drawn by Shu Hirose, who also wrote the prequels Grisaia no Kajitsu (The Fruit of Grisaia) and Grisaia no Meikyuu (The Labyrinth of Grisaia). The first chapter starts with Rena, Tohka, Chris and Murasaki hunting down a target.
Phantom Trigger is the newest part of the Grisaia series and tells the story of a group of girls who train at Mihama Academy to become members of SORD (Social Ops, Research & Development).
Official Grisaia: Phantom Trigger Website (English): http://grisaia-pt.com/en/index.html