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