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