Here is the full list of all 100 Busty Hentai Mosaic achievements.
Without a bra
Without underwear, <3
Undressed!
Shiniqua, 19
Outerwear
Without outerwear
Nishi, 22
Tsubasa, 21
Utano, 22
Maeko, 20
Koemi, 19
Emi, 20
Akem, 21
Hisoka, 23
Kana, 19
Mikasa, 20
Rin, 22
Sugi, 24
Tora, 19
Katsuki, 20
This is B
This is U
This is S
This is T
This is Y
Without Outerwear
<3