Here is the full list of all 37 Gal*Gun 2 achievements.
Reach the ending for the first time.
Finish Chiru's route B.
Get stepped on by 50 girls.
Get stepped on by 10 girls.
Get kissed by 50 girls.
Get kissed by 10 girls.
Perform a Lovestrike for the first time.
Clear all of the Kamizono Sisters' requests.
Upgrade your Demon Sweeper to its final form.
Take a good look from below when you have a girl over.
Give 30 girls Striphoria.
Call a girl over to your house for the first time.
Give 500 girls euphoria.
Clear your first Doki Dokie Mode.
Suck up 500 mini-demons.
Clear your first search mission.
Use the Demon Sweeper to give a girl Striphoria for the first time.
Clear your first defense mission.
Suck up 100 mini-demons.
Suck up a Metal Kurona for the first time.
Get 50 ecstacy shots in a row.
Give 100 girls euphoria.
Give a girl a snack for the first time.
Get 30 ecstacy shots in a row.
Clear your first regular mission.
Get an ecstacy shot for the first time.
Unlock all other achievements.
Reach Risu's good ending.
Finish Nanako's route A.
Finish Nanako's route B.
Finish Chiru's route A.
Reach the Harem ending.
Give 50 girls euphoria with Lovestrikes.
Upgrade your Pheromone Goggles to their final form.
Get every girls' phone number.
Have plenty of conversations with Chiru.
Have plenty of conversations with Nanako.