Here is the full list of all 23 Drain Mansion achievements.
Surrender yourself to an enemy you escaped from.
Get used to it.
Unlocked every entry in the gallery.
Set foot in the dungeons.
You don't have to press all of them...
Released a caged succubus... What did you expect?
Find the double jump shoes.
Get through the catgirl.
Reached the main area of the mansion.
Escape the silver haired succubus a second time.
Survive all of the Imp's trials.
Meet up with whom you were searching for.
Run away from the Succubus lord.
Scare away the shy Dragon Girl.
You survived the attacks of the Kunoichi.
Witness a calm doggo.
Found all the secret switches.
Found the Gardens area.
Read Emi's secret diary
See the normal ending.
See the true ending.
Remain pure until the very end.
Finish the game in hard mode.