Need Queen of Fighters achievement guide

[Martl]

I finished the game with Empress End (got Queen of Fighters title during first run ).
Then started new game with Warden Mode. First of all in new game i activated all titles with useful passives (no sex passives) and after that choose Queen of Fighters title. With Queen of Fighters title i finished the second run with good ending, but did not get achievement.
Sooo. What did i do wrong? How to get this achievement guaranteed (any advices/guides)?

[ThanatosX]

Challenges are started at the NG+ screen where you pick the difficulty and stuff. You don't get to change the title or you fail the challenge, it is locked but you can choose to cancel it.

[Kasiornis]

Finish the game. You will appear at NG+ screen. There will be 3 "guard" NPCs. Left one will reset your Karryn level to Level 1 - do that. Middle one will let you save the game in a different save slot - optional, I do that. Right one is a "challenge" NPC, choose the challenge you'd like to do.
Then choose the difficulty (Warden or Prisoner).
As mentioned above, because of the challenge you will be locked into a single title. All other titles which have passive effects will be working normally, but you won't be able to switch them (obviously) and won't be able to use those which need activation (equip once).

Do know that completing the challenge run not only rewards you with an achievement, but with a title as well.
Completing the challenge on Prisoner difficulty replaces this title with a stronger version, giving a bit more benefits, but just a bit. And this title will stay with you in all future playthroughts as well.

Also do know that one of the easiest way to complete this challenge is by going sex route, Endurance-focused build. The challenge prevents you from using halberd and related skills, but you won't be using it at all, because Endurance build is a "tank" build, basically a fool-proof option to complete any run and challenge. It's just a very slow, tedious option since you'll be watching a lot of the same scenes over and over again. But reliable, nonetheless.