Here is the full list of all 39 Gal*Gun: Double Peace achievements.
Make 50+ Girls Experience “Double Peace”
View the True Love Route's True Ending
View All of the True Endings
View Patako's True Ending
Receive a “Perfect!” Score VS Patako
Collect All of the Panties From the Changing Room
Defeat 100 Demon Girls
View Kurona's True Ending
Receive a “Perfect!” Score VS Kurona
View Ekoro's True Ending
Receive a “Perfect!” Score VS Ekoro
View Sisters Route's True Ending
Receive a “Perfect!” Score VS Shinobu & Maya
Get a Perfect Score on “Demon-Attracting Balm”
View Aoi's Ending
Get a Perfect Score on “Sisters' Odd Ritual”
Achieve Godlike Rank
View Maya's True Ending
Receive a “Perfect!” Score VS Maya
Receive a “Perfect!” Score VS Mr. Demon Balloon
Get a Perfect Score on “Maya's Medical Care”
Get a Perfect Score on “Maya's Demon Calling”
View Your First Ending
View Shinobu's True Ending
Experience Your First Final Doki-Doki Mode
Receive a “Perfect!” Score VS Shinobu
Give 500 Girls Euphoria
Receive a “Perfect!” Score VS Mr. Demon Veggie
Fire 1000 Pheromone Shots
Fulfill 10 of the Girls' Requests
Get a Perfect Score on “Her Majesty Shinobu”
Get a Perfect Score on “Shinobu in the Window”
Get a 30 Combo of Ecstasy Shots
Get 100 Ecstasy Shots
Experience Your First Doki-Doki Mode
Give a Girl Euphoria
Unlock All Trophies
Obtain All Images in the Gallery
Complete Profiles for Every Girl