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