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