Here is the full list of all 14 Soulslayer achievements.
Complete Yaohongyuan's route
Refuse to do anything until run out of chances
Complete Lady Xu's route
Complete Zhencheng's route
Complete Junyue's route
Complete main story and reach good ending
Eye for an eye
Make a successful deduction
Save all three from the fire
Poison yourself for all three times
Drink the poisonous soup twice
Reach a dead end
Complete all the routes
Complete tutorial level