Here is the full list of all 15 Hentai Lover's Train achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
First girl
Second girl
Third girl
Fourth girl
Fifth girl
Sixth girl
Seventh girl
Eighth girl
Ninth girl
Tenth girl
Eleventh girl
Twelfth girl
Thirteenth girl
Fourteenth girl
Fifteenth girl