Here is the full list of all 90 Gal*Gun VR achievements.
Reach rank 1 on the Stage 8 score ranking
Unlock all other achievements
Reach rank 1 on the Stage 7 score ranking
Give Michiyo Azuma euphoria 10 times
Reach rank 1 on the Stage 6 score ranking
Give Saori Fujino euphoria 10 times
Reach rank 1 on the Stage 5 score ranking
Reach rank 1 on the Stage 4 score ranking
Give Rena Kuribayashi euphoria 10 times
Take a picture of Yuko Yureino's panties
Take a picture of Rena Kuribayashi's panties
Take a picture of Michiyo Azuma's panties
Take a picture of Saori Fujino's panties
Take a picture of Shizuka Ninomiya's panties
Take a picture of Ren Yoshikawa's panties
Take a picture of Yuri Tsurugi's panties
Take a picture of Konomi Kujirai's panties
Take a picture of Mafuyu Yanagida's panties
Take a picture of Yurina Gozu's panties
Take a picture of Suzume Asano's panties
Take a picture of Madoka Tsukimiya's panties
Take a picture of Kazami Saijo's panties
Take a picture of Rikiko Tanaka's panties
Take a picture of Uraraka Nishibina's panties
Take a picture of Ruriko Mikasa's panties
Take a picture of Tsuzumi Murasame's panties
Take a picture of Maria Natsuki's panties
Take a picture of Neneko Kosugi's panties
Take a picture of Tsubomi Haruno's panties
Take a picture of Kanko Shishido's panties
Take a picture of Yukina Jinbo's panties
Take a picture of Mai Aoshima's panties
Take a picture of Otome Kurosawa's panties
Take a picture of Rion Harusame's panties
Take a picture of Tsukasa Nishiguchi's panties
Take a picture of Megumi Tendou's panties
Reach rank 1 on the Stage 3 score ranking
Suck up 500 Mini Kuronas
Reach rank 1 on the Stage 2 score ranking
Reach rank 1 on the Stage 1 score ranking
Give Tsuzumi Murasame euphoria 10 times
Give Tsukasa Nishiguchi euphoria 10 times
Give Anita Bellman euphoria 10 times
Clear Stage 8
Give Sayaka Nitta euphoria 10 times
Give Mafuyu Yanagida euphoria 10 times
Give Yuko Yureino euphoria 1 times
Give Midori Hanba euphoria 10 times
Give Maki Sudou euphoria 10 times
Clear Stage 7
Give Ren Yoshikawa euphoria 10 times
Give Yuri Tsurugi euphoria 10 times
Give Mai Aoshima euphoria 10 times
Give Madoka Tsukimiya euphoria 10 times
Give Kazami Saijo euphoria 10 times
Give Suzume Asano euphoria 10 times
Clear Stage 6
Give Otome Kurosawa euphoria 10 times
Give Konomi Kujirai euphoria 10 times
Give Neneko Kosugi euphoria 10 times
Give Shizuka Ninomiya euphoria 10 times
Give Ruriko Mikasa euphoria 10 times
Give Rion Harusame euphoria 10 times
Give Saki Takada euphoria 10 times
Give Megumi Tendou euphoria 10 times
Give Rikiko Tanaka euphoria 10 times
Give Uraraka Nishibina euphoria 10 times
Give Yukina Jinbo euphoria 10 times
Give Karen Sazanami euphoria 10 times
Clear Stage 5
Suck up your first Metal Mini Kurona
Give Maria Natsuki euphoria 10 times
Take a picture of Midori Hanba's panties
Give Kanko Shishido euphoria 10 times
Give Saori Fujiwara euphoria 10 times
Give Tsubomi Haruno euphoria 10 times
Suck up 100 Mini Kuronas
Clear Stage 4
Give Yurina Gozu euphoria 10 times
Clear Stage 3
Take a picture of Saori Fujiwara's panties
Clear Stage 2
Take a picture of Anita Bellman's panties
Take a picture of Saki Takada's panties
Take a picture of Sayaka Nitta's panties
Clear Stage 1
Take a picture of Maki Sudou's panties
Take a picture of Karen Sazanami's panties
Suck up your first Mini Kurona
Suck up your first Mr. Happiness