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