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