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