Here is the full list of all 48 Just Deserts achievements.
Reveal all story
Complete all game routes
Achieve “Harem” End
Reveal all CG
Complete Jennifer route
Complete Cecile route
Complete Yumi route
Complete Cornelia route
Complete Eve route
Reveal all character’s talk lines
Achieve "Infatuated" relationship with all heroines in 1 game
Defeat 150 aliens in 1 game
Complete 1 game (1 route)
Achieve "Single" End
Use Cornelia's Spear Fall support 4 times in 1 game
Achieve "Love" relationship with all heroines in 1 game
Use Cornelia's Spear Fall support in a battle
Defeat 50 aliens in 1 game
Have a meal 30 times in 1 game
Talk 300 times
Complete 30 Quests in 1 game
Kill 30 aliens with hand gun in 1 game
Give 30 erotic items
Buy 25 teddy bears or 25 polar bears in 1 game
Reach 5,000,000 million Bz cash
Win in 1 turn, 5 times in 1 game
Win 5 battles each in less than 4 turns in 1 game
Use medicine 25 times in 1 game
Give 30 packs of instant noodle
Give 20 disliked items to 1 heroine in 1 game
Give 10 disliked items to 1 heroine in 1 game
Buy 100 items
Buy 30 bottles of mineral water in 1 game
Reach 1,000,000 Bz cash
Get a Lucky Pendant
Talk 50 times
Run from battle 30 times in 1 game
Complete 40 Patrol Works in 1 game
Passed out 10 times in 1 game
Swimming 30 times in 1 game
Die before day 2
Workout 30 times in 1 game
Sleep in the morning for 20 days in 1 game
Shooting Practice 30 times in 1 game
Sleep in the morning for 10 days in 1 game
Has 0 Bz money
Sleep before night for 5 days in 1 game
Get money for the first time