Here is the full list of all 46 Conception PLUS: Maidens of the Twelve Stars achievements.
Obtain all achievements.
Obtain all weapons.
Complete all quests.
Use all Team Colors.
Give birth to the special class "Ninja."
Give birth to a Star Child of each class.
Complete Harem ending.
Complete Mirei's ending.
Obtain all armor.
Complete Reone's ending.
Obtain all accessories.
Complete Sue's ending.
Complete Mahiru's ending.
Complete a total of 100 Chain Combos.
Complete Tarua's ending.
Complete Collette's ending.
Complete Lillith's ending.
Complete Farun's ending.
Complete Femiruna's ending.
Complete Alfie's ending.
Complete Ruka's ending.
Give birth to 200 Star Children.
Complete Arie's ending.
Complete Yuzuha's ending.
Complete main scenario.
Complete Normal ending.
Clear 12 Constellation Labyrinths.
Have 100 Star Children go independent.
Give birth to the special class "Bondsman."
Perform the Tri-Mating ritual.
MECUNITE a total of 10 times.
Give birth to the special class "Dungeon Master."
Clear 6 Constellation Labyrinths.
Insta-kill 100 Impurities.
Give birth to the special class "Sage."
Clear 4 Constellation Labyrinths.
Have 25 Star Children go independent.
Clear 3 Constellation Labyrinths.
Clear 2 Constellation Labyrinths.
Clear 1 Constellation Labyrinth.
Visited the Map Point "Gift Shop."
Give birth to 12 Star Children.
Complete a total of 8 Chain Combos.
Visited the Map Point "Scavenger."
Visited the Map Point "Day Camp."
Give birth to your first Star Child.