Enter the game for the first time

Successfully resist 1 demon invasion

Self-explanatory, as far as achievements go. Just start the game, complete the first fight, and you're two achievements closer to 100 %.

These are self-explanatory, as well. To raise a character's rank, have two more of the same one on the same level and they'll fuse automatically. That means you will need a total of three of the same 1 star char for rank 2 and three 2 star chars for rank 3. Plan accordingly.

Note: It is very much possible to level all eight characters you're using to rank 3. Focus on raising your bank first to get more slots, while leveling up white chars early. Don't try to force it by rerolling the shop in the beginning.

Raise Iris' Rank to 3 Stars

Raise Ahern's Rank to 3 Stars

Raise Anno's Rank to 3 Stars

Raise Julia's Rank to 3 Stars

Raise Dahl's Rank to 3 Stars

Raise Nicole's Rank to 3 Stars

Raise Rose's Rank to 3 Stars

Raise Rosalind's Rank to 3 Stars

Raise White's Rank to 3 Stars

Raise Bertram's Rank to 3 Stars

Raise Sherry's Rank to 3 Stars

Raise Rand's Rank to 3 Stars

Raise Angel's Rank to 3 Stars

Raise Marian's Rank to 3 Stars

Raise Crystal's Rank to 3 Stars

Raise Annabel's Rank to 3 Stars

Raise Cora's Rank to 3 Stars

Raise Tabitha's Rank to 3 Stars

Raise Cara's Rank to 3 Stars

Raise Calvin's Rank to 3 Stars

Raise Alva's Rank to 3 Stars

Raise Baldwin's Rank to 3 Stars

This one's confusing for non-Chinese speakers. Baldwin's achievement has Bertram's icon for some reason.

Raise Dale's Rank to 3 Stars

Raise Sana's Rank to 3 Stars

Normal End

True End

Complete the game without any indulgences to reach the true end. Monsters will be stronger after the first time you resist the succubus' temptation and some characters will solicit you for "indulgences" over the course of the game. Turn them down, otherwise you're headed straight for the normal ending. Giving the succubus money is fine, though, so simp away when she kidnaps your chars.

爱吃萝卜的栗子 wrote a very helpful guide about this that explains a lot of the tactics behind it better than I could. You can find it here:
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=2839684855

City Wall Durability Reaches Zero

Desire Exceeds The Upper Limit

Hope Reaches Zero

Indulge Yourself 15 Times in one Game

"FIFTEEN TIMES?!", you say? In addition to the three visits from the succubus, you get one H scene with Anno and Calvin each, as long as you have recruited them, for a total of five automatically available ones. For the other ten, you will need the Prostitution skill available for purchase in the SwitchSkills menu under Bank. After purchasing it, equip it and use it whenever possible once your Bank is at Lvl. 3.