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