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