Here is the full list of all 29 Scarlet Maiden achievements.
Slay 200 enemies in one run
Completer the quest ‘It’s a Strap’
Defeat Queen Lily
Complete the quest ‘Green Delight’
Find 50 items in one run
Complete the quest ‘Magic Flute’
Level up to level 50
Gain 100000 sin total
Level Faelina to level 5
Slay 100 enemies in one run
Defeat the Grand Archivist
Level Roman to level 5
Gain 15000 sin in one run
Complete the quest ‘Masquerade’
Level Bruce to level 5
Earned after 10th run
Defeat the Earth Mother
Find 20 items in one run
Level up to level 10
Complete the quest ‘Steamy Contraptions’