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