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