In the game Treasure Hunter Claire, unfortunately you won't find anything called "Achievement", because that's the game. Besides "Achievement", this game presents something called "Title". In my mind, this can be said to be an achievement in the game, because in it there is an achievement for the main character, and an achievement for having finished the game. You can see the list of "Titles" below:

• 1. Treasure Hunter
  The first title that was obtained and was also Claire's nickname. Has no special effect.
  
  
• 2. Pervy Adventurer
  Complete the Prologue for the first time. The prologue is the part where Claire comes to Alstroemeria and visits the Goddess's Temple to get blessings or the power of heroes. Has the effect of +3 Desire when performing an action.
  
  
• 3. Diligent Adventurer
  Completing a quest for the first time. Has the effect of -5 Desire when performing an action.
  
  
• 4. Sex Novice
  Trying to have sex for the first time or several times. Has the effect of +10 Desire when performing an action.
  
  
• 5. Sex Practitioner
  Have sex for several times. Has the effect of +20 Desire when performing an action.
  
  
• 6. Sex Expert
  Have multiple or multiple sex (and this “Title” will reveal). Has the effect of +30 Desire when performing an action.
  
  
• 7. Tech Master
  Have had a lot of sex, maybe about 100 times (if it's not open yet, then keep trying). Has the effect of +50 Desire when performing an action.
  
  
• 8. Mouth Lover
  Use your mouth or tongue when doing H-scenes or sex. Has the effect of Mouth Sex Techniques Attack +5% (Used when in battle or battle mode).
  
  
• 9. Mouth Adept
  Use more of your mouth or tongue when doing H-scenes or sex. Has the effect of Mouth Sex Techniques Attack +15% (Used when in battle and battle mode).
  
  
• 10. Boob Lover
  Use your chest or breasts when doing H-scenes or sex. Has the effect of Breast Sex Techniques Attack +5% (Can be used when in battle or battle mode).
  
  
• 11. Boob Adept
  Use more of your chest or breasts when doing H-scenes or sex. Has the effect of Breast Sex Techniques Attack +15% (Can be used when in battle and battle mode).
  
  
• 12. P*ssy Lover
  Use your groin when having sex or H-scenes. Has an effect, namely Vag*na Sex Technique Attack +5% (Can be used when in battle and battle mode, the effect will be seen when using sex techniques against enemies).
  
  
• 13. Golden P*ssy
  Use more of the groin when having sex or H-scenes. Has an effect, namely Vag*na Sex Technique Attack +15% (Can be used when in battle and battle mode, the effect will be seen when using sex techniques against enemies).
  
  
• 14. A*s Lover
  Use your butt during sex or H-scenes. Has the effect of Butt Sex Technique Attack +5% (Used when in battle mode, and the effect will be seen when fighting enemies).
  
  
• 15. A*s Adept
  Use more, buttocks during sex or H-scenes. Has the effect of Butt Sex Technique Attack +15% (Used when in battle mode, and the effect will be seen when fighting enemies).
  
  
• 16. Fetish Addict
  Perform special games 30 times against people or monsters, counting for all the female characters. Has an effect, namely Special Sex Technique Attack + 5% (Used when in battle mode, and the effect will be seen when fighting enemies).
  
  
• 17. Allrounder
  Doing a special game 100 times against people or monsters, applies to all the existing female characters. Has the effect of Special Sex Technique Attack + 15% (Used when in battle mode, and the effect will be seen when fighting enemies).
  
  
• 18. Propositioner
  Doing the Proposition 30 times (Enter the Menu and select Proposition), can only be used on male NPCs. Has the effect of +30 Desire and +30 ml of milk.
  
  
• 19. Propostion Adept
  Doing Proposition 100 times (Enter Menu and select Proposition), can only be used on male NPCs. Has the effect of +50 Desire and +50 ml of milk.
  
  
• 20. Prostitute Adventurer
  Performing the Prostitute 50 times (Enter the Menu and Select Prostitute, to be able to do it first Claire must be in "Dom/Sub" status), can only be used on male NPCs. Has the effect of getting more money while doing the Prostitute.

• 21. A Little Domineering
  Obtained when you get "Dom" status, "Dom" status can also be obtained through potions sold in shops. Has the effect of +3 Dom when performing an action.
  
  
• 22. I Like to Dominate
  Obtained while having sex with multiple people and is in a "Dom" status. As a reference, it would be very easy to do it with the guys who are in the “House of Spectacles”, located behind Mr. Dietrich's residence. Has the effect of +5 Dom when performing the action.
  
  
• 23. Lustful Adventurer
  Obtained when getting "Sub" status, same as "Dom" status. "Sub" can also be obtained through potions sold in shops or when carrying out a quest from Raul. Has the effect of +3 Sub after performing the action.
  
  
• 24. Masochist Adventurer
  Obtained while having sex with a person and is in a “Sub” status. For example, try going to the Fresh Vegetable Seller on the North side of Alstromeria and join the Event. Has the effect of +5 Sub after performing the action.
  
  
• 25. Honest Adventurer
  Take off all existing clothes (naked). Has the effect of -20 Desire, and -5 Dom/Sub after taking action or after having sex.
  
  
• 26. Open Adventurer
  Lowered Shyness to 0 Points. Has the effect of adding Desire and Arousal.
  
  
• 27. Exhibitionist
  Lowered Shyness to 70 Points. Has the effect of -2 Shyness after performing the action.
  
  
• 28. Band of Nudists
  Gives a passionate effect on all party members, including Claire, the effect I mean is "Dom / Sub". Has the effect of being able to wear any clothes without having to pay attention to "Shyness" (Very useful if you do New Game+, so that at the beginning of the game, Claire can wear any clothes).
  
  
• 29. Righteous Adventurer
  Complete 25 Guild quests. Has the effect of -1 Karma after taking action.
  
  
• 30. S*men Collector
  Collect 3.000 ml of milk (Can be more or less). Has the effect of +30 ml of milk after taking action or after sex.
  
  
• 31. S*men Appreciation
  Gather 5.000 ml of milk (Could be more or less, I don't know for sure). Has the effect of +50 ml of milk after taking action or after sex.
  
  
• 32. S*men Lover
  Collect a total of 10.000 ml of milk (Yes, 10K ml of Milk). Has the effect of +100 ml of milk after taking action or after sex.
  
  
• 33. Industrious Adventurer
  Complete all Quests in the Guild (Total Quest totals 88). Has the effect of -30 Desire, -3 Dom/Sub, and -2 Karma after taking action or after sex.
  
  
• 34. Heroic Adventurer
  Can be obtained after completing the game for the first time, some conditions that must be met are Karma does not reach 100 points and does not have Dom/Sub status. Has the effect of -100 Desire, -10 Dom/Sub and Karma will not increase after taking action or after sex.
  
  
• 35. Superhero Adventurer
  Can be obtained after opening "True End" or seeing the ending story of Claire's story, to be able to get it requires several conditions such as: having finished the game for the first time and playing again in New Game+ Mode, maximizing all affection for Claire's friends (carrying out Quest Affection up to 5 hearts), has Karma under 15 points and not more, is not in a passionate state (Desire 0, Dom and Sub 0). For Shyness it doesn't really matter, either the points remain 100 or 0. It has the effect that Desire won't increase, Sub/Dom won't increase, and Karma won't increase.
  
  
• 36. Super Lewd Adventurer
  Can be obtained after clearing a game, either for the first time or in New Game+ Mode. The requirement that must be fulfilled is to have 100 Points against Dom or Sub, only one of them. Has the effect of +300 Desire, +10 Dom/Sub, +200 ml Milk, +5 Karma, and -3 Shyness after doing the action or after sex.
  
  
• 37. Traveler of Spacetime
  Obtained after completing the entire story of Treasure Hunter Claire. To be able to get it, you first have to reach the “True End” so that a new place will open called Demon's King Castle. Next is for you to go to the castle and defeat the Demon King and his servants. Has the effect of +500 Desire, +20 Dom/Sub, Milk +300 ml, can wear any clothes, and get more money from prostitution. The effect takes effect after taking action or after sex.
  
  NB:
  The meaning of "while taking action" is when you do your actions such as having sex and triggering the H-Scene, or making a Proposition and Prostitution. So that the final result you will get will be affected by the "Title" you have used. For example, if you use "Title - S*men Lover" if you get 200 ml s*men it will add 100 so that what you get is 300 ml, something like that.

There are things that are very influential with the achievement of "Ending" and some are not. Some things that are not affected are like "Shyness" and "S*men". To get an "Ending", you only need to pay attention to the status of "Desire", "Sub / Dom", and "Karma". These three things are important points to get through the "Ending" that you want to open. Collecting milk or "S*men" is an obligation or a common thing, because it is explained at the beginning of the game that to be able to use the strong power of a hero, Claire is ordered to go on an adventure collecting milk from people around her.

For your information, the “Ending” route started to trigger when fighting the Angel Boss in the Heavenly Temple. So, if you want to open a "Ending", set the "Status" required to reach a particular "Ending" route.

What I said above is based on the experiences I have had while playing the game. And I also have, one of the sources I use: https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=1610758339