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