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