Here is the full list of all 52 Jerez's Arena achievements.
True End
Win Ellin's third battle
Watched Ellin dance
Fed the birds with Claudia
Claudia completed her 20th Mercenary Commission
Win Ellin's second battle
Ellin completed her 30th Training
"Agility" reached 200!
Win Claudia's second battle
"Dexterity" reached 200!
"Willpower" reached 200!
"Stamina" reached 200!
"Strength" reached 200!
Win Ellin's first battle
Claudia completed her 30th Training
Accumulate 100000 G worth of wealth
Saved Ellin at the Tavern
Stopped the Noble from bullying Claudia
Bad End
Reach any Ending
Win Claudia's third battle
"Seduction" reached 200!
"Kinkiness" reached 200!
Claudia completed her 20th Prostitution Quest
"Obedience" reached 200!
"Technique" reached 200!
Ellin completed her 30th Conditioning
Win Claudia's first battle
"Lewdness" reached 200!
Claudia completed her 30th Conditioning
Completed Claudia's Oiran Request
Punished Ellin for stealing
Ellin completed her first Training
Ellin completed her first Mercenary Commission
Completed the Undercover Mansion Mission
Ellin completed her first Prostitution Quest
Claudia completed her first Mercenary Commission
Ellin completed her first "training" Conditioning
Ellin joined the team!
Completed the Bandit Mission
Claudia completed her first Prostitution Quest
Claudia completed her first Conditioning
Claudia completed her first Training
Ellin completed her 20th Prostitution Quest
Ellin completed her 20th Mercenary Commission
Claudia End
Ellin End
Earned All Achievements
Lose All Battles
Defeated Glenn at the height of his power in Conqueror Mode.
Defeated Isekai Adventurer Lica in Conqueror Mode.
Cleared Conqueror Mode.