Here is the full list of all 20 Hentai Tales: The Entrance To Isekai achievements.
Complete Level 4-5
Complete Level 4-4
Complete Level 4-3
Complete Level 4-2
Complete Level 4-1
Complete Level 3-5
Complete Level 3-4
Complete Level 3-3
Complete Level 3-2
Complete Level 3-1
Complete Level 2-5
Complete Level 2-4
Complete Level 2-3
Complete Level 2-2
Complete Level 2-1
Complete Level 1-5
Complete Level 1-4
Complete Level 1-3
Complete Level 1-2
Complete Level 1-1